Chapter II: Magnitudes of the Stars (1)

The apparent brightness of a star, as we see it from the earth, depends upon two causes--its intrinsic brilliancy or the quantity of light which it actually emits, and its distance from us. It follows that if all the stars were of equal intrinsic brightness we could determine their relative distances by measuring the respective amounts of light which we receive from them. The quantity of light in such a case varies inversely as the square of the distance. This will be made evident by Fig. 1, where S represents the position of a star, regarded as a luminous point, while A and B are screens placed at such a distance that each will receive the same amount of light from the star. If the screen B is twice as far as the screen A, its sides must be twice as large as those of A in order that it shall receive all the light that would fall on A. In this case its surface will be four times the surface of A. It is then evident that any small portion of the surface of B will receive one fourth as much light as an equal portion of surface A. Thus an eye or a telescope in the position B will receive from the star one fourth as much light as in the position A, and the star will seem one fourth as bright.

The fact is, however, that the stars are very unequal in their actual brightness, and in consequence the apparent magnitude of a star gives us no clue to its distance. Among the nearer of the stars are some scarcely, if at all, visible to the naked eye, while among the brighter ones are several whose distances are immeasurably great. A remarkable example is that of Caropes, the second brightest star in the heavens.

For these reasons astronomers are obliged to content themselves, in the first place, with determinations of the actual amount of light that the various stars send to us, or their apparent brilliancy, without regard to their distance or actual brilliancy. The ancient astronomers divided all the stars they could see into six classes, the number expressing the apparent brightness being called the magnitude of the star. The brightest ones, numbering in all about fourteen, were said to be of the first magnitude. The fifty next in brightness were said to be of the second magnitude. Three times as many, an order fainter, were of the third magnitude. The progression was continued up to the sixth magnitude, which included those which were barely visible.

As the stars are actually of every degree of apparent brilliancy, no sharp line of demarkation could be drawn between those of one magnitude and those of the magnitude next higher. Hence, different observers made different estimates, some calling a star of the second magnitude which others would call of the first, while others would designate a star of the third magnitude which others would call of the second. It is therefore impossible to state with absolute numerical precision what number of stars should be regarded of one magnitude and what of another.

An idea of the magnitude of a star can be readily gained by the casual observer. Looking at the heavens on almost any cloudless evening, we may assume that the two, three or more brightest stars which we see are of the first magnitude. As examples of those of the second magnitude, may be taken the five brightest stars of the Dipper, the Pole Star and the brighter stars of Cassiopeia. Some or all of these objects can be seen on any clear night of the year in our latitude. Stars of the third magnitude are so numerous that it is difficult to select any one for comparison. The brightest star of the Pleiades is really of this magnitude, but it does not appear so in consequence of the five other stars by which it is surrounded. At a distance of 15° from the Pole Star, Beta Ursa Minoris is always visible, and may be distinguished by being slightly redder than the Pole Star; it lies between two fainter stars, the brighter of which is of the third and the other of the fourth magnitude. The five readily visible but fainter stars of the Pleiades are about of the fourth magnitude. Of the fifth magnitude are the faintest stars which are easily visible to the naked eye, while the sixth comprises those which are barely visible with good eyes.

Modern astronomers, while adhering to the general system which has come down to them from ancient times, have sought to give it greater definiteness. Careful study showed that the actual amount of light corresponding to the different magnitudes varied nearly in geometrical progression from one magnitude to another, a conclusion which accords with the well-known psychological law that the intensity of sensation varies by equal amounts when the exciting cause varies in geometrical progression. It was found that an average star of the fifth magnitude gave between two and three times as much light as an average one of the sixth; one of the fourth gave between two and three times as much light as one of the fifth; and so on to the second. In the case of the first magnitude, the diversity is so great that it is scarcely possible to fix an average ratio. Sirius, for example, is really six times as bright as Altair, which is commonly taken as a standard for a first magnitude star. To give precision to their estimates, modern astronomers are gradually seeking to lay the subject of magnitudes on an exact basis by defining a change of one unit in the magnitude as corresponding to an increase of about two and one half times in the amount of light.

If the practice of separating the visible stars into only six orders of magnitude were continued without change, we should still have the anomaly of including in one class stars of markedly different degrees of brightness. Some more than twice as bright as others would be designated of the same magnitude. Hence, to give quantitative exactness to the results, a magnitude is regarded as a quantity which may have any value whatever, and may be expressed by decimals--tenths or even hundredths. Thus, we may have stars of magnitude 5.0, 5.1, 5.2, etc., or we may even subdivide yet farther and speak of stars having magnitudes 5.11, 5.12, etc. Unfortunately, however, there is as yet no way known of determining the amount of light received from a star except by an estimate of its effect upon the eye. Two stars are regarded as equal when they appear to the eye of equal brilliancy. In such a case the judgment is very uncertain. Hence, observers have endeavored to give greater precision to it by the use of photometers,--instruments for measuring quantities of light. But even with this instrument the observer must depend upon an estimated equality of light as judged by the eye. The light from one star is increased or diminished in a known proportion until it appears equal to that of another star, which may be an artificial one produced by the flame of a candle. The proportion of increase or diminution shows the difference of magnitude between the two stars.

As we proceed to place the subject of photometric measures of star light on this precise basis we find the problem to be a complex one. In the first place not all the rays which come from a star are visible to our eyes as light. But all the radiance, visible or invisible, may be absorbed by a dark surface, and will then show its effect by heating that surface. The most perfect measure of the radiance of a star would therefore be the amount of heat which it conveys, because this expresses what is going on in the body better than the amount of visible light can do. But unfortunately the heating effect of the rays from a star is far below what can be measured or even indicated by any known instrument. We are therefore obliged to abandon any thought of determining the total amount of radiation and confine ourselves to that portion which we call light.

Here, when we aim at precision, we find that light, as we understand it, is properly measured only by its effect on the optic nerve, and there is no way of measuring this effect except by estimation. Thus, all the photometer can do is to give us the means of increasing or diminishing the light from one star, so that we can make it equal by estimation to that from some other star or source of light.

The difficulty of reaching strict results in this way is increased by the fact that stars are different in color. Two lights can be estimated as equal with greater precision when they are of the same color than when their colors are different. An additional source of uncertainty is brought in by what is known as the Purkinje phenomenon, after the physicist who first observed it. He found that if we took two lights of equal apparent brightness, the one red and the other green, and then increased or diminished them in the same proportion, they would no longer appear equal. In other words, the geometrical axiom that halves or quarters of equal quantities are themselves equal, does not apply to the effect of light on the eye. If we diminish the two equal lights, we find that the green will look brighter than the red. If we increase them in the same proportion, the red will look brighter than the green. In other words, the red light will, to our vision, increase or fade away more rapidly with a given amount of change than the green light will.

It is found in recent times that this law of change does not extend progressively through all spectral colors. It is true that as we pass from the red to the violet end of the spectrum the yellow fades away less rapidly with a given diminution than does the red, and the green still less rapidly than the yellow. But when we pass from the green to the blue, it is said that the latter does not fade out quite so fast as the green.

One obvious conclusion from all this is that two stars of different colors which look equal to the naked eye will not look equal in the telescope. The red or yellow star will look relatively brighter in a telescope; the green or bluish one relatively brighter to the naked eye.

In recent times stars have been photographed on a large scale. Their magnitudes can then be determined by the effect of the light on the photographic plate, the impression of the star, as seen in a microscope, being larger and more intense as the star is brighter. But the magnitude thus determined is not proportional to the apparent brightness as seen by the eye, because the photographic effect of blue light is much greater than that of red light having the same apparent brightness. In fact, the difference is so great that, with the chemicals formerly used, red light was almost without photographic effect. Even now, what we measure in taking the photograph of a star is almost entirely the light in the more refrangible portions of the spectrum. It appears, therefore, that when a blue and a yellow star, equally bright to the naked eye, are photographed, the impression made on the negative by the blue star will be greater than that made by the yellow one. A distinction is therefore recognized between photographic and visual magnitudes.

The photographic magnitudes of the stars are now being investigated and catalogued on a scale even larger than that on which we have studied the visual magnitudes. Yet we have to admit the non-correspondence of the two systems. The bluer the star, the brighter will be its photographic as compared with its visual magnitude. The most that can be done is to bring about the best attainable agreement between the two systems in the general average of all the stars.

Fortunately the differences between the colors of the stars are by no means so great as those between the colors of natural objects around us. All the stars radiate light of all colors; and although the difference is quite appreciable either by the eye or by the photograph, it is not so great as it would have been were the variations in color as wide as in the case of terrestrial objects.

Two comprehensive surveys of the heavens, intended to determine as accurately as possible the magnitudes of all the brighter stars, have recently been undertaken. One of these is the Harvard photometry, commenced by Professor Pickering at the Harvard Observatory, and now extended to the Southern Hemisphere by the aid of a branch establishment at Arequipa, Peru.

The instrument designed by Professor Pickering for his purpose is termed a meridian photometer, and is so arranged that the observer can see in the field of his telescope a reflected image of the Pole Star, and, at the same time, the image of some other star while it is passing the meridian. By a polarizing apparatus the image of the star to be measured is made to appear of equal brightness with that of the Pole Star, and the position of a Nicol prism, which brings out this equality, shows the ratio between the magnitudes of the two stars.

The other survey, with the same object, is now being made at the Potsdam Astrophysical Observatory, near Berlin. In the photometer used by the German astronomers the image of one star is compared with an artificial star formed by the flame of a candle. The work is performed in a more elaborate way than at the Harvard Observatory, and in consequence, only that part of the heavens, extending from the equator to 40° north declination, has been completed and published. A comparison of the results thus obtained with those of Professor Pickering, shows a curious difference depending on the color of the star. In the case of the reddest stars, the estimates are found to be in fairly close agreement, Pickering’s being a little the fainter. But in the case of the white or bluish stars, the estimates of the German astronomers are more than one fourth of a magnitude greater than those of Pickering. This corresponds to an increase of nearly one fifth in the brightness. Whether this difference is to be regarded as purely psychological or due to the instruments used, is an interesting question which has not yet been settled. It is difficult to conceive how different instruments should give results so different. On the other hand, the comparisons made by the Germans make it difficult to accept the view that the difference is due purely to the personality of the observers. There are two German observers, Drs. Müller and Kempf, whose results agree with each other exactly. On the other hand, Pritchard, at Oxford, made quite an extensive photometric survey, using an instrument by which the light of one star was cut down by a wedge-shaped dark glass, whereby any gradation of light could be produced. A comparison shows that the results of Pritchard agree substantially with those of Pickering. It is quite possible that the Purkinje phenomenon may be the cause of the difference, the source of which is eminently worthy of investigation.

This fact simply emphasizes the lack of mathematical precision in photometric measurements of star light. Even apart from this difference of color, the estimates of two observers will frequently differ by 0.2 and sometimes by even 0.3 of a magnitude. These differences correspond roughly to 20 or 30 per cent in the amount of light.

It must not be supposed from this that such estimates are of no value for scientific purposes. Very important conclusions, based on great numbers of stars, may be drawn even from these uncertain quantities. Yet, it can hardly be doubted that if the light of a star could be measured from time to time to its thousandth part, conclusions of yet greater value and interest might be drawn from the measures.

We have said that in our modern system the aim has been to so designate the magnitudes of the stars that a series of magnitudes in arithmetical progression shall correspond to quantities of light ranging in geometrical progression. We have also said that a change of one unit of magnitude corresponds to a multiplication or division of the light by about 2.5. On any scale of magnitude this factor of multiplication constitutes the light-ratio of the scale. In recent times, after much discussion of the subject and many comparisons of photometric measures with estimates made in the old-fashioned way, there is a general agreement among observers to fix the light ratio at the number whose logarithm is 0.4. This is such that an increase of five units in the number expressing the magnitude corresponds to a division of the light by 100. If, for example, we take a standard star of magnitude one and another of magnitude six, the first would be 100 times as bright as the second. This corresponds to a light ratio slightly greater than 2.5.

When this scale is adopted, the series of magnitudes may extend indefinitely in both directions so that to every apparent brightness there will be a certain magnitude. For example, if we assign the magnitude 1.0 to a certain star, taken as a standard, which would formerly have been called a star of the first magnitude, then a star a little more than 2.5 times as bright would be of magnitude one less in number, that is, of magnitude 0. The one next brighter in the series would be of magnitude -1. So great is the diversity in the brightness of the stars formerly called of the first magnitude that Sirius is still brighter than the imaginary star just mentioned, the number expressing its magnitude being -1.4.

This suggests what we may regard as one of the capital questions in celestial photometry. There being no limit to the extent of the scale, what would be the stellar magnitude of the sun as we see it when expressed this way on the photometric scale? Such a number is readily derivable when we know the ratio between the light of the sun and that of a star of known magnitude. Many attempts have been made by observers to obtain this ratio; but the problem is one of great difficulty, and the results have been extremely discordant. Amongst them there are three which seem less liable to error than others; those of Wollaston, Bond and Zöllner. Their results for the stellar magnitude of the sun are as follow:

Wollaston -26.6
Bond -25.8
Zöllner -26.6

Of these, Zöllner’s seems to be the best, and may, therefore, in taking the mean, be entitled to double weight. The result will then be:

Stellar magnitude of sun -26.4

From this number may be readily computed the ratio of sunlight to that of a star of any given magnitude. We thus find:

The sun gives us:

10,000,000,000, the light of Sirius.
91,000,000,000, the light of a star of magnitude 1.
9,100,000,000,000, the light of one of magnitude 6.

The square roots of these numbers show the number of times we should increase the actual distance of the sun in order that it might shine as a star of the corresponding magnitude. These numbers and the corresponding parallax are as follows:

Sirius; Distance = 100,000: Parallax = 2″.06
Mag. 1 ” 302,000: ” 0″.68
” 2 ” 479,000: ” 0″.43
” 3 ” 759,000: ” 0″.27
” 4 ” 1,202,000: ” 0″.17
” 5 ” 1,906,000: ” 0″.11
” 6 ” 3,020,000: ” 0″.07

These parallaxes are those that the sun would have if placed at such a distance as to shine with the brightness indicated in the first column. They are generally larger than those of stars of the corresponding magnitudes, from which we conclude that the sun is smaller than the brighter of the stars.

PREVENTIVE INOCULATION. (II.)

BY DR. W. M. HAFFKINE,

DIRECTOR-IN-CHIEF, GOVERNMENT PLAGUE RESEARCH LABORATORY, BOMBAY.

In a previous paper I reviewed briefly the history of preventive inoculation and described the results of my attempts to secure a ‘virus fixé’ in the case of cholera. It will be remembered that the two vaccines finally obtained protected guinea pigs successfully against all possible forms of cholera infection.

It was now necessary to ascertain whether the same protection could be given to man which was observed in animals. For this purpose it was essential to first of all prove the perfect harmlessness of the operation. This was established by very careful observations of medical men and scientists who were inoculated in Europe soon after the results of the above investigations were published. The inoculation causes a rise of temperature and general discomfort, which lasts one or two days, and some pain at the seat of the injection, which disappears in a few days. The fever and discomfort induced are, on the whole, shorter in duration, though often more intense, than those caused by vaccination against smallpox. The effect disappears within a few days and the individual returns to his usual condition of health.

The next and all-important stage was to devise an experiment or a series of experiments on man so as to test the efficiency of the method against cholera attacks. This part of the investigation could only be done in a cholera-stricken country, where opportunities would arise of comparing the incidence of the disease in inoculated and uninoculated. Such opportunities are limited. Except in certain parts of India and China, cholera appears in localities unexpectedly and does not last long. In the places where the disease is endemic the cases are scattered over large areas. These features rendered the demonstration of the effect of the vaccine a matter of particular difficulty. In 1893 I went to India, and in the course of a year inoculated some twenty-three thousand people in the northern parts of the country; but no cholera appeared in their midst to show whether the vaccine was of value or not. In the spring of 1894 the inoculations were introduced into Bengal, and, with the assistance and co-operation of Prof. W. J. Simpson, of King’s College, London, at that time Health Officer of Calcutta, and of his staff, efforts were made to induce the inhabitants of the _bustees_ of Calcutta to get themselves inoculated. These bustees are isolated villages consisting of groups of mud huts inhabited by the poorer class. Owing to the consumption of water from the ponds or tanks belonging to these villages, the inhabitants of the bustees are subject to periodic visitations of cholera. It was in one of these bustees that the first observation was made as to the effect of the cholera vaccines.

The spring is essentially the cholera season in Calcutta. About the end of March two fatal cases of cholera and two cases of choleraic diarrhœa occurred in Katal Bagan Bustee, in a population grouped around two tanks. This outbreak led to the inoculation of one hundred and sixteen persons in the bustee out of about two hundred. After the inoculation there occurred nine more cases of cholera, seven of which proved fatal, and one case of choleraic diarrhœa. All the ten cases occurred among the uninoculated portion of the inhabitants, which formed the minority, none of the inoculated suffering. The results were more interesting when analyzed in detail. Some of the cases had occurred in families in which some of the members had been inoculated and others not, and the disease selected the non-inoculated members, sparing the inoculated. Thus, in one house six members out of eight had been inoculated. The attack, a fatal one, occurred in one of the remaining two. In another house eleven members out of eighteen were inoculated. The eleven members remained free while four out of seven not inoculated were attacked.

Upon these observations the Calcutta municipality felt encouraged to vote funds for the continuance of the inoculations in an experimental farm, and appointed for that purpose a special staff. In 1896 the result of two years’ observations were embodied by the health officer in a report to the Calcutta Municipal Corporation. It recorded a most satisfactory state of affairs. During the time under observation some eight thousand persons were inoculated. Cases of cholera occurred in seventy-seven huts in which some members of the family had been previously inoculated and others not. Comparing the incidence of the disease in the two groups, a striking advantage was found to be with the inoculated. I made an analysis of the cases according to the time which had elapsed between inoculation in each of these huts and the occurrence of cholera in them, and the following results were found. During the first four days after inoculation, apparently before the vaccine had time to produce its full protective effect, there were proportionately 1.86 times fewer deaths among the inoculated than among the non-inoculated members of the families. In a second period, extending from the fifth to the four hundred and twenty-ninth day--i. e., for fourteen months--there were 22.62 times fewer deaths among the inoculated; while in the last period--that is, between the four hundred and thirtieth and seven hundred and twenty-eighth day after the inoculation--there were only 1.54 fewer deaths among the inoculated, the immunity having evidently gradually disappeared. The net result was that for two years after inoculation, including the periods of incomplete protection, there was a reduction in mortality of 72.47 per cent among the inoculated; or in other words, in houses in which inoculations were performed and in which cholera subsequently occurred there were, even from the day of inoculation, before the full effect of it could be produced, eleven deaths among the non-inoculated to only three among the inoculated. Eight lives out of every eleven were saved.

At the end of my first cholera campaign, in August, 1895, there were altogether 31,056 natives of India, 125 Eurasians, 869 Europeans of the civil population, 6,627 native officers and sepoys, and 294 officers with 3,206 men of the British troops stationed in India, in all 41,787 people, who had submitted to inoculation. Observations instituted among them, especially among prisoners, soldiers and coolies in tea estates, with regard to whom detailed records could be kept, went to confirm the results as detailed above. In order to lengthen, if possible, the period of immunity, the plan was formed of inoculating stronger vaccines and in higher doses. The inoculations are now carried on in a Government laboratory, in Purulia, Bengal, chiefly among the people emigrating to the cholera districts of Assam, and there is no doubt that in the course of time a marked effect upon the prevalence of cholera in those districts will be produced and valuable theoretical data will be obtained.

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There was one noticeable feature about the results of the inoculation against cholera which early attracted my attention, and this was that while the number of attacks and the absolute number of deaths was strikingly influenced by the operation, the proportion of deaths to those attacked did not appear to be changed. The case incidence was effectively checked, but the ‘case mortality’ was not reduced. The inoculation diminished the chances of an attack of cholera--that is, the chances of the cholera virus penetrating into the tissues of a man; but if it so happened that the patient was attacked and the virus found an entrance and started growing in the system notwithstanding the inoculation, the latter would not assist in mitigating the severity of the symptoms or reducing the fatality of the disease. In analyzing this result further, it seemed to me permissible to assume that the vaccine protected against the cholera microbes themselves, but did not protect against their poisonous products, which are the cause of the actual symptoms.

This interpretation of the facts found support in a set of laboratory experiments by Professor Pfeiffer and Dr. Kolle, of Koch’s Institute, in Berlin, who showed that the blood serum of animals and persons inoculated with the cholera vaccine, as practiced in India, acquired an intense power of destroying cholera microbes, but exhibited no properties capable of counteracting the effect of their toxic products--no ‘antitoxic properties’. Combined with those of previous experimenters these results tended to prove that two kinds of immunity could be produced separately, and it became incumbent to devise a plan which would secure not only a lowering of susceptibility to the disease, but also a reduction in the case mortality.

For that purpose it seemed rational to attempt the treatment with a vaccine containing a combination of bodies of microbes, together with their toxic products. I intended to test this plan experimentally in the cholera districts; but, plague having broken out in Bombay, the Government of India commissioned me to inquire into the bacteriology of that disease, and I determined that the knowledge gained in the cholera inoculations should be applied and tested in the preparation of a prophylactic against the new epidemic.

The experiments I had in view involved manufacturing a material on a large scale, and operating on it for weeks continuously. To do this it was essential to find a way of recognizing plague growth with certainty, so as to enable the officers engaged in the manufacture to control the process and know exactly when they were handling the proper stuff, and when an admixture and invasion of extraneous growth took place. When this was solved, a drug was prepared by cultivating the plague microbe in sterilized broth, to which a small quantity of clarified butter or of cocoanut oil had been added. The plague bacilli attach themselves to the drops of butter or oil floating on the surface, and grow down into the depth of the liquid, forming a peculiar threadlike appearance. While doing so they secrete toxic matter, which is gradually accumulated in the liquid; at the same time a large amount of microbial growth comes gradually down from the surface of the liquid and collects at the bottom of the flask. When shaken up the whole represents the desired combination of the bodies of microbes and of their toxic products. The process is continued for a period of five to six weeks. As the microbes of plague had been very little studied before, and as their exact effect on the human system was unknown, I decided not to use for the treatment living microbes, but to use at least at first ‘carbolized’ vaccines, though the result of the treatment might be less favorable or less lasting than that which could be expected from living vaccines. The microbes in the above plague growth were accordingly killed by heating them at a temperature ranging from 65° to 70° C., and then mixed with a small proportion of carbolic acid, to prevent the drug from subsequent contamination and decomposition. The dose of the prophylactic was regulated by measuring up the quantity to be injected. The requisite amount is determined by the degree of fever which it produces. The febrile reaction varies in different individuals, but a temperature reaching 102° and above in at least thirty per cent of those inoculated has been found to indicate a good material. In the cholera, rabies and smallpox vaccines, the microbes being employed in a living state, it was essential to fix the strength of the vaccine, for otherwise it was impossible to predict the behavior of the microbe when injected into the system. In the case of the plague prophylactic the activity of the microbes is arrested before it is inoculated, and the effect can be regulated, as mentioned above, by simply measuring up the doses in the same way as is done with any chemical drug.

The expectation formed when devising the plan for the plague prophylactic has been very fortunately justified, and an advance on the results from the cholera vaccines was obtained; but I can not yet say certainly whether this favorable result is indeed due to the particular provisions which I had made for obtaining it.

The effect of the plague prophylactic was first tested at the Byculla Jail, in Bombay, when the epidemic reached that establishment. From the first day after the inoculation till the end of the outbreak there were in the jail twelve cases and six deaths among one hundred and seventy-two uninoculated inmates, and two cases, with no deaths, among one hundred and forty-seven inoculated. A year later, almost exactly a similar result was observed when the plague attacked the so-called Umarkhadi Common Jail, in Bombay. In this case after the inoculation there were ten cases and six deaths among one hundred and twenty-seven uninoculated inmates, and three cases, with no deaths, among one hundred and forty-seven inoculated. These and other observations show that the vaccine for the plague begins to exercise its effect within some twenty-four hours after inoculation; that it is useful even in the case of persons already infected; that it is therefore applicable at any stage of an epidemic. Numerous further observations were soon collected on the working of the system.

At the small village of Uudhera, of the Baroda feudatory state, where plague broke out, inoculation was applied to a half of each family, the other half remaining uninoculated. After that there were twenty-seven cases and twenty-six deaths among sixty-four uninoculated, and eight cases, with three deaths, among seventy-one inoculated of the same households, the proportionate difference in mortality being over eighty-nine per cent. There followed observations on a far larger scale, demonstrating that the mortality of the inoculated, compared to that of the non-inoculated, was on an average between eighty and ninety per cent less. Sometimes this reduction reached ninety per cent. In the Punjaub, in a village called Bunga, there occurred, in two hundred and eighty-one not inoculated, ninety-seven cases of plague and sixty-five deaths, while among seventy-four inoculated there were six cases, but no deaths. In Bangalore, among 80,285 of the inhabitants not inoculated, there were 2,208 deaths from plague, while among 23,537 inoculated there were only 108. The observations at Lanowli, Kirkee, Daman, Hubli, Dharwar, Gadag, in the Bombay Presidency, gave the same results. At Hubli over forty-two thousand inhabitants out of some fifty thousand were inoculated. In Bombay city, out of a population of 821,764, 157,256 have now undergone the inoculation. The work proceeds here at present at the rate of one thousand to eleven hundred inoculations a day.

From plague hospitals the returns show that among those of the attacked who were previously inoculated the mortality is reduced to less than one half of that among patients who were not inoculated. The property of reducing the case mortality thus appears to belong to the plague prophylactic in an unmistakable degree.

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By the anti-cholera and anti-plague inoculation the methods of preventive treatment by means of cultivated bacteria and their products have been rendered, so to say, a part of the daily policy in human medicine. The usefulness and practicability of those methods have become clearly apparent, and steps have been taken to extend further the field of their application. On the ground of the experiments made with the typhoid bacillus in the Pasteur Institute in 1889-’93, and of the results obtained from the anti-cholera inoculation in India, I was able to induce Professor Wright, of the Pathological Laboratory in Netley, whom I initiated in 1892 in the principles and technique of anti-cholera inoculation, to start a campaign of similar operations against typhoid among the British troops. The latter are stationed at different times of their service very nearly in all parts of the world, and yearly pay a very heavy tribute to that disease. The medical officers in charge of these troops pass through a course of training at Netley, and Professor Wright had rendered excellent services in connection with the cholera inoculations, by disseminating the knowledge of them among the probationers of the school. It seemed to me expedient, therefore, to start the typhoid inoculation also through the staff and pupils of that school. The following plan as to the preparation of the vaccine, and the way of carrying out the inoculation, was laid before Professor Wright. The typhoid bacillus was to be brought to a fixed stage of virulence by the inoculation in the peritoneal cavity of Guinea pigs, according to the exact rules prescribed for the anti-cholera inoculation. Once the virus was fixed, it was to be cultivated for twenty-four hours on a solid medium, and a first vaccine prepared by carbolizing that virus. As, however, the durability of the effect of carbolized vaccine alone was not known, this was to be followed up by the injection of a dose of the fixed living virus.

The inoculation was first to be made on volunteers among the physicians on probation at Netley; then on volunteers among the young officers of the army on the eve of their departure for the tropics; and then, with the approval of the military authorities, on volunteers among private soldiers. At the end of 1895, during my visit to England, I obtained from Sir William Mackinnon, then Director-General of the Army Medical Department, permission for Professor Wright to start the work upon the plan above detailed; and the first inoculations, in the way described above, were done in the middle of 1896. Soon after that, Pfeiffer and Kolle, recognizing the same similarity between the cholera and typhoid microbes, and pointing out that the results obtained by us in India were likely to be repeated when applying the method to typhoid, proposed and started a similar series of inoculations.

When the inoculation against plague was begun, and observation showed that dead vaccines alone were apparently sufficient to produce satisfactory results, a second inoculation with living virus appeared less urgently necessary; and as the effect of such an inoculation, which Professor Wright very courageously tried first on himself, seemed troublesome, it was decided to do for the time being the second inoculation also with the carbolized virus. Similarly, the plan which was adopted for the plague inoculation, of cultivating the vaccine in a liquid, instead of a solid medium, and of using cultures of several weeks’ duration, has been subsequently adopted in the typhoid inoculation also.

Many thousands of British soldiers and civilians have already undergone the inoculation in question. The latter was done partly with vaccines cultivated on a solid medium, according to the older plan, and partly with vaccines prepared according to the plague inoculation method. The results so far observed are encouraging, and, I hope, will shortly be improved considerably. At the last Harveian dinner in London, Surgeon-General Jameson, Director-General of the Army Medical Department, summarized the results of the observations in India, where, among several thousands of young soldiers, the most prone to the disease, the incidence of typhoid since their inoculation was 0.7 per mille, while among the older, more resistant, not inoculated soldiers, the incidence was during the same period just double that. A large proportion of the force now on service in the South African campaign have been inoculated, some before embarking and others on their way out.

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Such is the position of preventive inoculation, as applied, so far, to human communities. The very success of these operations is now apt to create some sort of feigned or earnest alarm, and one meets at present with the question, What is going to happen to our poor body if we are to be inoculated against _all_ diseases? and with this other one, How do you expect us to make a _living_ if you try to keep all of us alive? The humorous form of these questions usually permits of their dropping out of the conversation without a reply. The earnest answers are, however, obvious. The efforts of the bacteriologists in combating diseases are at present directed to a twofold aim: their prevention, by a prophylactic treatment, and their cure. The advantage of a curative treatment is that it is to be applied to a relatively small number of persons, to those who actually fall victims to an attack; while that of the preventive treatment is in the greater certainty with which safety and protection are secured by it. The relative position of the two treatments will, in practice, differ in different diseases--namely, according to the prevalence and fatality of a given disease, and according to the merits of the two treatments as they stand at the time. In diseases in which the risks of being attacked are smaller, or the consequences of an attack less serious, or for which a very effective and sure curative treatment has been discovered, the majority of people will prefer to wait for an actual attack rather than to undergo the discomfort of a preventive treatment; in diseases, on the contrary, in which the chances of being attacked are great, or in which the fatality is higher, the sequelæ of an attack more serious, and for which a successful and not very troublesome preventive treatment has been found, large numbers will undergo preventive inoculation. But, even in the latter case, a mutual co-operation between the two methods will exist always, as there will always be a number of people, either among those who have neglected to protect themselves by inoculation, or among those in whom the inoculation has proved unsuccessful, who will fall victims to an attack and require the benefits of a curative treatment, be those at the time little or great.

The answer to the second question is of course to be expected rather from the politico-economist, the wise administrator, the civilian, than from the bacteriologist. In any case it is clear already that if we are ever to be told that we must thin our ranks, we shall prefer not to leave the task in the hands of the indiscriminating microbe, but to have some voice in the matter ourselves. Inoculation marks only the conquest of another force which henceforth we shall be glad to control.

BOMBAY, INDIA, _March, 1900_.

COLONIES AND THE MOTHER COUNTRY. (II.)

BY JAMES COLLIER.

The growth of the relations between a colony and the mother country closely follows the development of the relationship between an organism and its offspring, or (in higher species) between parents and children. When an infusorian subdivides into two cells, the new cell produced swims away and henceforth leads an independent life. Most of the Phœnician and most of the earlier Greek colonies were social infusoria which parted from the parent organism by segmentation and had no further relations with it. As we rise in the animal scale a new relationship, that between mother and young, and a new instinct, the maternal, come into existence. These begin as low down as the mollusks, and expand and heighten, though not without strange lapses, in both insects and birds as species develope; but we need not trace the evolution here. Let it suffice to note that there are successive degrees of specialization; a site is chosen suitable for depositing and hatching eggs; means are found for making them secure; a shelter is built for them; they are deposited near substances adapted to nourish the young; special food is prepared for them; they are reared through food disgorged or brought to them. The accession of the male to the family marks the dawn of the paternal instinct; it appears earliest among fishes. This evolution is repeated in the history of colonies, where, however, the maternal and paternal offices melt into one another insensibly.

The mother country founds and nurtures colonies. Most of the earliest colonies are the work of adventurous bands or navigating merchants or fishermen, who seek their own habitats, carry with them their own equipment and fight their own battles. Then the metropolis settles its surplus or discontented citizens in territories previously chosen, provides them with all that is necessary for their start, and often nourishes them during the infancy of the colony. Hispaniola was a state colony manned with miners and artisans who were provided with tools, and this at the cost of a loan and a draught from the confiscated property of the Jews. Nor was it until gold began to be found in large quantities that the receipts equalled the expenditure on the young colony. Louisiana was founded and fostered with a royal munificence that conferred on it “more than was contributed by all the English monarchs together for the twelve English colonies on the Atlantic.” Georgia was a one-man foundation, but the British Parliament twice granted considerable sums to initiate it and carry it on; the Society for the Propagation of the Gospel aided, and the benevolence of philanthropic England contributed largely to its success. Not till 1818--more than half a century after the conquest--did the revenue of Canada balance its expenditure. The convict colony of New South Wales was, of course, entirely of state origin. Stores of every kind, together with cattle and seeds, were sent out at the beginning, and long continued to be sent out to it. The first governor was granted a space of two years to make it self-supporting, but the growth of a convict colony is abnormally slow, and the civil and military establishments for thirty-four years continued to be a drain on the British exchequer to the extent of over ten millions. Even now one of the oldest and best of existing British colonies, with an area of over three hundred thousand square miles, does not produce the breadstuffs needed for its own consumption. The Cape of Good Hope, of mixed Dutch and French origin, was first made a truly British colony by the dispatch of six thousand emigrants at the cost of the mother country--a cost much greater than was anticipated. When the Transvaal was forcibly annexed by England, the stepmother country advanced a sum of £90,000 to rescue the quondam republic from its financial difficulties. In 1895 Parliament voted three millions for the building of a railroad in British East Africa. Uganda is supported by a British subsidy. Algeria is a manufactured colony, which has all along had to be supported by its creator. Apart from the cost of their civil and military establishments, France has to subsidize her colonies to the extent of over four millions sterling, partially expended in reproductive public works. Even tiny New Caledonia costs France half a million, one half of which, it is true, is expended on the convict establishment.

Most colonies at their beginning are burdensome to the mother country. Years after its foundation South Australia fell into such embarrassment that its governors had to draw on the imperial exchequer for nearly a million. In 1834 the expenditure in Cape Colony was still in excess of the revenue. Sierra Leone had to be aided by a parliamentary grant year after year. No wonder the Colonial Office complained that colonies were expensive to keep up. In German Africa the revenue does not meet the expenditure. The Congo Free State does not pay its way. On the other hand, Congo Française has a substantial surplus. Western Australia was another exception to the rule. There the Imperial Government announced that it would contribute nothing to the foundation of the colony, which was to be self-supporting from the first. Private capitalists were to arrange for the emigration of ten thousand persons in four years. Lands were granted to the emigrants on a scale of extravagance which long hampered the progress of the colony. Companies likewise expend large sums in many colonies. French and English companies embarked on American, Indian, African and island adventures at ruinous loss. Law’s company withdrew from Louisiana, the New Zealand Company from New Zealand, and the Canterbury Association from Canterbury with a balance on the wrong side of the account. Wealthy individuals bear their part. Mr. Rhodes annually subsidizes the British Central African Protectorate, and King Leopold the Congo Free State. Colonial bishoprics have also been endowed and colonial cathedrals built, largely with the aid of voluntary contributions by sympathizers in the mother country.

The mother state sometimes gives the colonies the benefit of her financial good name. In 1869 England withdrew her regiments from New Zealand when the colony was still at war with the Maoris, and to salve the wounded feelings of the colonists she agreed (under pressure) to guarantee a loan of a million in aid of emigration and public works. Before the Canadian Pacific Railway could be completed the Imperial Government had to guarantee a loan of £3,600,000. Mr. Rhodes proposes (unsuccessfully, it now appears) that the Imperial Government, which contributed £200,000 to the cost of a railway from Kimberley to Buluwayo, should guarantee a loan of an enormous amount for the continuation of the African trunk railway from Buluwayo to Lake Tanganyika.

The mother country supports or aids its self-governing colonies through its capitalists. In order to execute public works--roads, bridges and railways--to assist immigration, to build fortresses, and sometimes to pay the interest on previous loans, all the colonies have habitual recourse to the British Stock Exchange. There are good reasons for this. The colonies have little capital of their own, for all their money has been used up from day to day. The English investor has an almost unlimited amount--the savings mainly of one industrious century--and he is prepared to lend it at a lower rate of interest than would content the colonial capitalist. Of over two thousand millions sterling which John Bull has out at usury all over the world, the total public and private indebtedness of the seven Australasian colonies alone, with a population of four millions, is stated to exceed three hundred and twenty millions, or at the rate of eighty pounds per head of these daring colonists. One half of this sum is due from colonial governments for the purposes already named. The half of it, due from banks, building companies, mercantile associations and mortgage agencies, excites no misgivings; these institutions can always go bankrupt, as many of them did in the financial collapse of 1891-’93. But it is not open to a British colony to file its schedules, or at least so we used to think; and so the Times said till the oldest of British colonies went bankrupt the other day. At all events, it is harder, and we contemplate this enormous pile of public indebtedness in young and scantily peopled communities with the same feelings as made alarmists foresee impending ruin in the growing augmentation of the gigantic public debt of the United Kingdom. It is commonly said that while the imperial debt has been accumulated as the cost of “just and necessary wars,” or of wars that were neither just nor necessary, the colonial debt has been contracted for the execution of reproductive public works. This is not altogether so. Eleven million pounds of the public debt of New Zealand were contracted to carry on war with the Maoris, who were defending their territory. The Seven Years’ War, which was begun on the part of England to gain possession of the Ohio Valley and thus increase the extent of her colonies, doubled her public debt. Where is the difference between the two classes of expenditure? Then most of the self-governing colonies have expended large sums in fortifying ports, some in partly supporting a fleet, and one at least in purchasing war ships of its own. Nor has all the remainder been reproductively expended. The building of schools is a wise way of spending money, one’s own or another’s, but it can not be called a materially reproductive way. Governors’ and ministerial residences, parliamentary and departmental buildings, are indispensable, but they can not be called ‘assets,’ especially if built of perishable and inflammable timber. Even railways, most profitable of public works, are not always true assets. In many of the colonies they are light railways, and when traffic increases and a higher speed is required they will have to be built over again and new rolling stock procured. Not a few of them, too, are ‘political railways,’ running through a sparsely populated country no-whither, and built to capture votes. Roads are only less valuable, but they were made (sometimes by graduates and men of scientific antecedents who were afterward cabinet ministers) at the wage rate of from two guineas to four pounds ten per week, and are an inadequate return on the outlay. Last century British loans were issued as prizes to friends of ministers, and a much reduced amount found its way to the treasury. Deduct an analogous, though not quite similar, item of waste in colonial loans, add this to all the other non-reproductive elements, and the genuinely reproductive proportion will shrink considerably. Every one of the colonies, even with the fee simple of territories only less than Europe in extent in their hands, would have sunk under the increasing burden. Happily or not, the ever-growing wealth of England has so cheapened money that the interest charge on the whole Australasian indebtedness sank in five years (1890-’96), mainly through conversion of loans, from fourteen millions to twelve and a quarter. It may be added that the colonies which have borrowed most recklessly have not been the most populous or those with largest resources, but rather the socialistic colonies with big schemes on hand.