Chapter XII: TECHNOLOGY.--Firing Points of Various Explosives.--The (3)

When they are all put in series, so that the battery has a much greater resistance than the rest of the circuit, the current rises much more rapidly, because of the smallness of the time constant, although it never attains the same ultimate maximum as when grouped in the other way. That is to say, if there is self-induction as well as resistance in the circuit, the amateur rule does not tell you the best way of arranging the battery. There is another mode of regarding the matter which is helpful. Self-induction, while the current is growing, acts as if there were a sort of spurious addition to the resistance of the circuit; and while the current is dying away it acts of course in the other way, as if there were a subtraction from the resistance. Therefore you ought to arrange the battery so that the internal resistance is equal to the real resistance of the circuit, plus the spurious resistance during that time. But how much is the spurious resistance during that time? It is a resistance proportional to the time that has elapsed since the current was turned on. So then it comes to a question of the length of time for which you want to work it. What fraction of a second do you require your signal to be given in? What is the rate of the vibrator of your electric bell? Suppose you have settled that point, and that the short time during which the current is required to rise is called t; then the apparent resistance at time t after the current is turned on is given by the formula:

R_{t} = R × e^{(R/L)t} + ( e^{(R/L)t} - 1 )

TIME CONSTANTS OF ELECTROMAGNETS.

I may here refer to some determinations made by M. Vaschy,[1] respecting the coefficients of self-induction of the electromagnets of a number of pieces of telegraphic apparatus. Of these I must only quote one result, which is very significant. It relates to the electromagnet of a Morse receiver of the pattern habitually used on the French telegraph lines.

L, in quadrants.
Bobbins, separately, without iron cores. 0.233 and 0.265
Bobbins, separately, with iron cores. 1.65 and 1.71
Bobbins, with cores joined by yoke,
coils in series 6.37
Bobbins, with armature resting on poles. 10.68

[Footnote 1: "Bulletin de la Societe Internationale des Electriciens," 1886.]

It is interesting to note how the perfecting of the magnetic circuit increases the self-induction.

Thanks to the kindness of Mr. Preece, I have been furnished with some most valuable information about the coefficients of self-induction, and the resistance of the standard pattern of relays, and other instruments which are used in the British postal telegraph service, from which data one is able to say exactly what the time constants of those instruments will be on a given circuit, and how long in their case the current will take to rise to any given fraction of its final value. Here let me refer to a very capital paper by Mr. Preece in an old number of the "Journal of the Society of Telegraph Engineers," a paper "On Shunts," in which he treats this question, not as perfectly as it could now be treated with the fuller knowledge we have in 1890 about the coefficients of self-induction, but in a very useful and practical way. He showed most completely that the more perfect the magnetic circuit is--though of course you are getting more magnetism from your current--the more is that current retarded. Mr. Preece'e mode of experiment was extremely simple. He observed the throw of the galvanometer when the circuit which contained the battery and the electromagnet was opened by a key which at the same moment connected the electromagnet wires to the galvanometer. The throw of the galvanometer was assumed to represent the extra current which flowed out. Fig. 56 represents a few of the results of Mr. Preece's paper.

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FIG. 56.--ELECTROMAGNETS OF RELAY, AND THEIR EFFECTS.

Take from an ordinary relay a coil, with its iron core, half the electromagnet, so to speak, without any yoke or armature. Connect it up as described, and observe the throw given to the galvanometer. The amount of throw obtained from the single coil was taken as unity, and all others were compared with it. If you join up two such coils as they are usually joined, in series, but without any iron yoke across the cores, the throw was 17. Putting the iron yoke across the cores, to constitute a horseshoe form, 496 was the throw; that is to say, the tendency of this electromagnet to retard the current was 496 times as great as that of the simple coil. But when an armature was put over the top, the effect ran up to 2,238. By the mere device of putting the coils in parallel, instead of in series, the 2,238 came down to 502, a little less than the quarter value which would have been expected. Lastly, when the armature and yoke were both of them split in the middle, as is done in fact in all the standard patterns of the British postal telegraph relays, the throw of the galvanometer was brought down from 502 to 26. Relays so constructed will work excessively rapidly. Mr. Preece states that with the old pattern of relay having so much self-induction as to give a galvanometer throw of 1,688, the speed of signaling was only from 50 to 60 words per minute, whereas, with the standard relays constructed on the new plan, the speed of signaling is from 400 to 450 words per minute. It is a very interesting and beautiful result to arrive at from the experimental study of these magnetic circuits.

SHORT CORES _versus_ LONG CORES.

In considering the forms that are best for rapid action, it ought to be mentioned that the effects of hysteresis in retarding changes in the magnetization of iron cores are much more noticeable in the case of nearly closed magnetic circuits than in short pieces. Electromagnets with iron armatures in contact across their poles will retain, after the current has been cut off, a very large part of their magnetism, even if the cores be of the softest of iron. But so soon as the armature is wrenched off, the magnetism disappears. An air gap in a magnetic circuit always tends to hasten demagnetizing. A magnetic circuit composed of a long air path and a short iron path demagnetizes itself much more rapidly than one composed of a short air path and a long iron path. In long pieces of iron the mutual action of the various parts tends to keep in them any magnetization that they may possess; hence they are less readily demagnetized. In short pieces, where these mutual actions are feeble or almost absent, the magnetization is less stable, and disappears almost instantly on the cessation of the magnetizing force. Short bits and small spheres of iron have no magnetic memory. Hence the cause of the commonly received opinion among telegraph engineers that for rapid work electromagnets must have short cores. As we have seen, the only reason for employing long cores is to afford the requisite length for winding the wire which is necessary for carrying the needful circulation of current to force the magnetism across the air gaps. If, for the sake of rapidity of action, length has to be sacrificed, then the coils must be heaped up more thickly on the short cores. The electromagnets in American patterns of telegraphic apparatus usually have shorter cores, and a relatively greater thickness of winding upon them, than those of European patterns.

* * * * *

ELECTRIC ERYGMASCOPE.

The erygmascope is the name of an electric lighting apparatus designed for the examination of the strata of earth traversed by boring apparatus.

It consists of a very powerful incandescent lamp inclosed in a metallic cylinder. One of the two semi-cylindrical sides constitutes the reflector, and the other, which is of thick glass, allows of the passage of the luminous rays, which thus illuminate with great brilliancy the strata of earth traversed by the instrument. The base, which is inclined at an angle of 45°, is an elliptical mirror, and the top, of straight section, is open in order to permit the observer standing at the mouth of the well, and provided with a powerful spyglass, to see in the mirror the image of the earth. The lamp is so mounted that its upwardly emitted rays are intercepted.

The whole apparatus is suspended from a long cable, formed of two conducting wires, which winds around a windlass with metallic journals which are electrically insulated. These journals communicate, through the intermedium of two friction springs, with the conductors on the one hand and, on the other, with the poles of an automatic and portable battery.

This permits of lowering and raising the apparatus at will, without derangement, and without its being necessary to interrupt the light and the observation.--_Revue Industrielle._

* * * * *

A NEW ELECTRIC BALLISTIC TARGET.

The electrical target usually employed in determining velocities of projectiles consists of a wooden frame on which is strung a copper wire so as to make a continuous circuit arranged in parallel vertical lines about one inch or one and one half inches apart.

It frequently happens that a projectile will pass through this target without breaking the circuit, either by squeezing between the wires or because, when last repaired, the target was short-circuited unnoticed, so that the cutting of the wires did not break the circuit. The repair of this target takes considerable time.

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Besides these objections to this target, another and more serious one is the irregularity in the manner of breaking the circuit. It has been proved that times required for a flat headed and an ogival headed projectile to rupture the current are very different.

To remedy these defects a new and very ingenious target has been devised and used with great success at the United States Military Academy at West Point. The top of the target is a wooden strip, F, on the upper side of which are screwed strips of copper, A A, about 1/2 in. wide, and 1/8 in. thick. The connection between two adjoining strips is made by a copper cartridge, C, which is dropped in a hole in the frame bored to receive it. This cartridge is the one used in the Springfield rifle. Inside the cartridge is a spiral spring, S, which, acting on the bottom of the hole and the head of the cartridge, tends to make the latter spring up, and so break the circuit.

To the hook, H, which is attached to the cartridge, is suspended, by means of a string, the lead weight, W, thus drawing down the cartridge and making the circuit between A and A'. All the weights being suspended the current comes in through the post, P, passes along the copper strips and out of the corresponding post on the other end.

On firing the projectile cuts a string, and the spring at once causes the cartridge to spring up, thus breaking the circuit.

It is not possible for the projectile to squeeze between the strings and not break the current, for in so doing the cartridge is tipped slightly, which is sufficient, as it breaks the current on one side.

This target is used in connection with the Boulenge chronograph. Two targets are established at a known distance apart, say 50 ft., and the time required for the projectile to pass over this distance is determined by finding the difference in the time of cutting of the two targets, by finding the difference in the time of falling of the two rods, caused by the demagnetization of two electromagnets in the same circuit with the targets.

By means of a disjunctor both rods are dropped at the same time, the shorter one releasing a knife blade which makes a cut on the longer one. Now both rods are hung from the magnets again and the gun is fired.

The projectile passes through the first target, breaks the circuit, demagnetizes the magnet of the longer rod, and it begins to fall. On passing through the second target, the projectile causes the shorter rod to fall. This releases the knife blade, and a second cut is made. The time corresponding to the distance between these cuts is the time the longer rod was falling before the second rod began to fall or the time between the cutting of the two targets by the projectile.

The distance between the cuts is measured, and the time corresponding to it can easily be found. Then the velocity of the projectile is equal to 50/t.

To repair this target, strings are prepared in advance of suitable length and looped at both ends, so that by placing the hook of the cartridge in one loop and that of the weight in the other the repair is quickly made.

This target has been used on the West Point proving ground to determine velocities over distances of 100 ft. interval to distances of only 9 ft. interval, and has given most satisfactory results.

* * * * *

[Continued from SUPPLEMENT, No. 786, page 12566.]

THE OUTLOOK FOR APPLIED ENTOMOLOGY.

[Footnote: Address of Dr. C.V. Riley at the annual meeting of the Association of Economic Entomologists, Champaign, Ills., November 11 to 14, 1890.]

LEGISLATION.

The amount of legislation in different countries that has of late years been deemed necessary or sufficiently important, in view of injurious insects, is a striking evidence of the increased attention paid to applied entomology; and while modern legislation of this kind has been, on the whole, far more intelligent than similar efforts in years gone by, many of the laws passed have nevertheless been unwise, futile, and impracticable, and even unnecessarily oppressive to other interests. The chief danger here is the intervention of politics or political methods. Expert counsel should guide our legislators and the steps taken should be thorough in order to be effective. We have had of late years in Germany very good evidence of the excellent results flowing from thorough methods, and the recent legislation in Massachusetts against the gypsy moth (_Ocneria dispar_), which at one time threatened to become farcical, has, fortunately, proved more than usually successful; the commission appointed to deal with the subject having worked with energy and followed competent advice.

PUBLICATION.

On the question of publication of the results of our labors it is perhaps premature to dwell at length. Each of the experiment stations is publishing its own bulletins and reports quite independently of the others, but after a uniform plan recommended by the association with which we meet here; and with but one exception that has come to my notice, another important recommendation of the same association--that these publications shall be void of all personal matter--has been kept in mind. The National Bureau of Experiment Stations at Washington is doing what it can with the means at command to further the general work by issuing the Experiment Station Record, devoted chiefly to digests of the State station bulletins. There is a serious question in my mind as to the utility of State digests by the national department of results already published extensively by the different States and distributed under government frank to all similar institutions and to whomsoever is interested enough to ask for them.

Such digests may or may not be intelligently made, and, even under the most favorable circumstances, will hardly serve any other purpose than helping to the reference to the original articles, and this could undoubtedly be done more satisfactorily to the stations and to the people at large by general and classified indices to all the State documents, made as full as possible and issued at stated intervals. Only a small proportion of the bulletins have been so far noticed by digest in this record, with no particular rule, so far as I can see, in the selection. In point of fact, those will be most apt to be noticed whose authors can find time to themselves send or make for the purpose their own abstracts. This is, perhaps, inevitable under present arrangements. Complete and satisfactory digests of all, if intelligent and critical, imply a far greater force than is at present at Prof. Atwater's command.

Under these circumstances, it would seem wiser to devote all the energies of the bureau to digests of the similar literature of other countries, which would be of immense advantage to our people and to the different station workers. Judging from the recommendations and resolutions of the general association, this is the view very generally held, but except in chemistry and special industries like that of beet sugar, very little of that kind of work has yet been attempted.

What is true of the station publications in general is equally true of special publications. As entomologist of the department, I have been urged to bring together, at stated intervals, digests of the entomological publications of the different stations. Such digests to be of any value, however, should also be critical, and it were a thankless task for any one to be critic or censor even of that which needs correction or criticism. Moreover, to do this work intelligently would require increase of the divisional force, which at present is more advantageously employed, for, as already intimated, I should have great doubts of the utility of these digests.

I believe, however, that the division should strive for such increase of means as would justify the periodic publication, either independently or as a part of the department record, of general and classified indices to the entomological matter of the station bulletins, and should work more and more toward giving results from other parts of the world. This could, perhaps, best be done by titles of subject and of author so spaced and printed on stout paper that they could be cut and used in the ordinary card catalogue. The recipient could cut and systematically place the titles as fast as received.

As to the character of the matter of the entomological bulletins, it will inevitably be influenced by the needs and demands of the people of the respective States, and while originality should be kept in mind, there must needs be in the earlier years of the work much restatement of what is already well known. That some results have been published of work which reflects no particular credit upon our calling is a mere incident of the new positions created. Yet we may expect marked improvement from year to year in this direction, and without being invidious, I would cite those of Prof. Gillette's on his spraying experiments and on the plum curculio and plum gouger, as models of what such bulletins should be.

Although the resolution offered at our last meeting by Prof. Cook, to the effect that purely descriptive matter should be excluded from the station bulletins, met with no favor, but was laid on the table, by the general association, I am in full sympathy with this position and am strongly of the opinion that in the ordinary bulletins such purely technical and descriptive matter should be reduced to the necessary minimum consistent with clearness of statement and accuracy, and that if it is desired, on the part of the station entomologists, to issue technical and descriptive papers, a separate series of bulletins were better instituted for this class of matter.

Finally, for results which it is desired to promptly get before the people, the agricultural press is at our disposal, and so far as the entomological work of the department of agriculture is concerned, the periodical bulletin, _Insect Life_, was established for this purpose. Its columns are open to all station workers, and I would here appeal to the members of the association to help make it, as far as possible, national, by sending brief notes and digests of their work as it progresses. Hitherto we have been unable to make as much effort in this direction as we desired, but in future it is our hope to make the bulletin, as far as possible, a national medium through which the results of work done in all parts of the country may quickly be put on record and distributed, not only to all parts of our own country, but to all parts of the world.

The rapid growth and development of the national department and the multiplication of its divisions have necessitated special modes of publication and rendered the annual report almost an anachronism so far as it pretends to be what it at one time was--a pretty complete report of the scientific and other work of the department. The attempts which I have made through the proper authorities to get Congress to order more pretentious monographic works in quarto volume similar to those issued by other departments of the government have not met with encouragement, and in this direction many of the stations will, let us hope, be able to do better.

CO-OPERATION.

Every other subject that might be considered on this occasion must be subordinate to the one great question of co-operation. With the large increase of actual workers in our favorite field, distributed all over the country, the necessity for some co-operation and co-ordination must be apparent to every one. Just how this should be brought about or in what direction we may work toward it, will be for this association in its deliberations to decide. Nor will I venture to anticipate the deliberations and conclusions of the special committee appointed to take the matter into consideration, beyond the statement that there are many directions in which we can adopt plans for mutual benefit. Take, for instance, the introduction and dissemination of parasites. How much greater will be the chance of success in any particular case if we have all the different station entomologists interested in some specific plan to be carried out in co-operation with the national department, which ought to have better facilities of introducing specimens to foreign countries or to different sections of our own country than any of the State stations.

Let us suppose that the fruit growers of one section of the country, comprising several States in area, need the benefit in their warfare against any particularly injurious insect of such natural enemy or enemies as are known to help the fruit growers of some other section. There will certainly be much greater chances of success in the carrying out of any scheme of introduction if all the workers in the one section may be called upon through some central or national body to help in the introduction and disposition of the desired material into the other section. Or, take the case of the boll worm investigation already alluded to. The chances of success would be much greater if the entomologists in all the States interested were to give some attention to such lepidopterous larvæ as are found to be affected with contagious diseases and to follow out some specific plan of cultivating and transmitting them to the party or parties with whom the actual trials are intrusted. The argument applies with still greater force to any international efforts. I need hardly multiply instances. There is, it is true, nothing to prevent any individual station entomologist from requesting co-operation of the other stations, nor is there anything to prevent the national department from doing likewise; but in all organization results are more apt to flow from the power to direct rather than from mere liberty to request or to plead. The station entomologist may be engrossed in some line of research which he deems of more importance to the people of his State, and may resent being called upon to divert his energies; and with no central or national power to decide upon plans of co-operation for the common weal, we are left to voluntary methods, mutually devised, and it is here that this association can, it seems to me, most fully justify its organization. And this brings me to the question of

THE DEPARTMENT AND THE STATIONS.

Immediately connected with the question of co-operation is the relation of the National Department of Agriculture and the State experiment stations. The relation, instead of being vital and authoritative, is, in reality, a subordinate one. Many persons interested in the advancement of agriculture foresaw the advantage of having experiment stations attached to the State agricultural colleges founded under the Morrill act of 1862; but I think that in the minds of most persons the establishment of these stations implied some such connection with the national department as that outlined in an address on Agricultural Advancement in the United States, which I had the honor to deliver in 1879 before the National Agricultural Congress, at Rochester, and in which the following language was used:

"In the light of the past history of the German experimental
stations and their work, or of that in our own State of
Connecticut, the expediency of purchasing an experimental farm of
large dimensions in the vicinity of Washington is very
questionable. There can be no doubt, however, of the value of a
good experimental station there that shall have its branches in
every State of the Union. The results to flow from such stations
will not depend upon the number of acres at command, and it will
be far wiser and more economical for the commissioner to make each
agricultural college that accepted the government endowment
auxiliary to the national bureau, so that the experimental farm
that is now, or should be, connected with each of these
institutions might be at its service and under the general
management of the superintendent of the main station. There is
reason to believe that the directors of these colleges would
cheerfully have them constituted as experimental stations under
the direction of the department, and thus help to make it really
national--the head of a vast system that should ramify through all
parts of the land....

"With the different State agricultural colleges, and the State
agricultural societies, or boards, we have every advantage for
building up a national bureau of agriculture worthy of the country
and its vast productive interests, and on a thoroughly economical
basis, such as that of Prussia, for instance."

In short, the view in mind was something in the nature of that which has since been adopted by our neighbors of the North, where there is a central or national station or farm at Ottawa and sub-stations or branch farms at Nappan, Nova Scotia, Brandon, Manitoba, Indian Head, N.W.T., and Agassiz, British Columbia, all under the able direction of Mr. William Saunders, one of our esteemed fellow workers. It was my privilege to be a good deal with Mr. Saunders when he was in Europe studying the experience of other countries in this matter, and the policy finally adopted in Canada as a result of his labors is an eminently wise one, preventing some of the difficulties and dangers which beset our plan, whether as between State and nation or college and station.

Under the present laws and with the vast influence which the Association of Agricultural Colleges and Experiment Stations will wield, both in Congress and in the different States, there is great danger of transposition, in this agricultural body politic, of those parts which in the animal body are denominated head and tail, and the old saw to the effect that "the dog wags the tail because the tail cannot wag the dog," will find another application. So far as the law goes, the national department, which should hold a truly national position toward State agricultural institutions depending on federal support, can do little except by suggestion, whether in the line of directing plans or in any way co-ordinating or controlling the work of the different stations throughout the country. The men who influenced and shaped the legislation which resulted in the Hatch bill were careful that the department's function should be to indicate, not to dictate; to advise and assist, not to govern or regulate. We have, therefore, to depend on such relationships and such plans of co-operation as will appear advantageous to all concerned, and these can best be brought about through such associations as are now in convention here.

Without such plans there is great danger of such waste of energy and means and duplication of results as will bring the work into popular disfavor and invite disintegration, for already there is a growing feeling that agricultural experiment is and will be subordinated to the ordinary college work in the disposition of the federal appropriations.

What is true of the national department as a whole in its connection with the State stations is true in a greater or less degree of the different divisions of the department in connection with the different specialists of the stations. With the multiplicity of workers in any given direction in the different States, the necessity for national work lessens. A favorite scheme of mine in the past, for instance (and one I am glad to say fully indorsed by Prof. Willits), was to endeavor to have a permanent agent located in every section of the country that was sufficiently distinctive in its agricultural resources and climate, or, as a yet further elaboration of the same plan, one in each of the more important agricultural States. The necessity for such State agents has been lessened, if not obviated, by the Hatch bill, and the subsequent modifications looking to permanent appropriations to the State stations or colleges, which give no central power at Washington. The question then arises, What function shall the national department perform? Its influence and field for usefulness have been lessened rather than augmented in the lines of actual investigation in very many directions. Many a State is already far better equipped both as to valuable surrounding land, laboratory and library facilities, more liberal salaries, and greater freedom from red tape, administrative routine, and restrictions as to expenditures, than we are at Washington; and, except as a directing agent and a useful servant, I cannot see where the future growth of the department's influence is to be outside of those federal functions which are executive. Just what that directing influence is to be is the question of the hour, not only in the broader but in the special sense. The same question, in a narrower sense, had arisen in the case of the few States which employed State entomologists. In the event, for instance, of an outbreak of some injurious insect, or in the event of any particular economic entomological question within the limits of the State having such an officer, the United States entomologist would naturally feel that any effort on his part would be unnecessary, or might even be looked upon as an interference. He would feel that there was always danger of mere duplication of observation or experiment, except where appealed to for aid or co-operation. This is, perhaps, true only of insects which are local or sectional, and is rather a narrow view of the matter, but it is one brought home from experience, and is certainly to be considered in our future plans. The favor with which the museum work of the national division was viewed by you at the meeting last November and the amount of material sent on for determination would indicate that the building up of a grand national reference collection will be most useful to the station workers. But to do this satisfactorily we need your co-operation, and I appeal to all entomologists to aid in this effort by sending duplicates of their types to Washington, and thus more fully insuring against ultimate loss thereof.

STATUS OF OUR SOCIETY.

This train of thought brings up the question of the status of our society with the station entomologists as represented by the committee of the general association. Those of us who had desired a national association for the various purposes for which such associations are formed, felt, I believe, if I may speak for them, that the creation of the different experimental stations rendered such an organization feasible. Your organization at Toronto and the constitution adopted and amended at the meeting at Washington all indicate that the chief object was the advancement of our chosen work and that the strength of the association would come from the experiment station entomologists. There was then no other organization of the kind, nor any intimation that such a one would be founded. Some of us therefore were surprised to learn from the circular sent out by Prof. Forbes, its chairman, that the committee appointed by the association of agricultural colleges and experiment stations, and through which we had hoped to communicate and co-operate with that association, was not in the proper sense a committee, but a section which has prepared (and in fact was required by the executive committee and the rules of the superior body to prepare) a programme of papers and discussions for the meeting to be held at the same time and place with our own. I cannot but feel that this is in some respects a misfortune, and it will devolve upon you to decide upon several questions of importance that will materially affect our future existence. That there is not room for two national organizations having the same objects in view and meeting at the same time and place goes, I think, without saying; and if the committee of the general association is to be anything more than a committee in the proper sense of the word, or if it is to assume with or without formal constitution the functions of our own association, then our own must necessarily be crippled, and to do any good at all must meet at a different time and a different place. A committee or section, or whatever it may be called, of the general association with which we meet, would preclude active membership of any but those who come within the constitution of that body. Our Canadian friends and many others who have identified themselves with applied entomology, and do not belong to any of our State or government institutions, would be debarred from active representation, however liberal the association may have been in inviting such to participate, without power to vote in its deliberations. Our own association has, or should have, no such limitations. Some of us who are entitled to membership in both bodies may feel indifferent as to the course finally decided upon, and that it will not make any difference whether we have an outside and independent organization, as that of the association of official chemists, or whether we do, as did the botanists and horticulturists, waive independence in favor of more direct connection with the general association, provided there is some way whereby the committees of the general association are given sufficient latitude and time to properly present their papers and deliberate; but there are others who feel more sensitive as to their action and are more immediately influenced by the feelings of the main body. I hope that whatever action be taken at this meeting, the general good and the promotion of economic entomology will be kept in mind and that no sectional or personal feeling will be allowed to influence our deliberations.

SUGGESTION AND COMMENT.

You will, I know, pardon me if, before concluding these remarks, I venture to make a few comments which, though not altogether agreeable, are made in all sincerity and in the hope of doing good. The question as to how far purely technical and especially descriptive and monographic work should be done by the different stations or by the national department is one which I have already alluded to and upon which we shall probably hold differing opinions, and which will be settled according to the views of the authorities at the different stations. Individually, I have ever felt that one ostensibly engaged in applied entomology and paid by the State or national government to the end that he may benefit the agricultural community can be true to his trust only by largely overcoming the pleasure of entomological work having no practical bearing. I would, therefore, draw the line at descriptive work except where it is incidental to the economic work and for the purpose of giving accuracy to the popular and economic statements. This would make our work essentially biological, for all biologic investigation would be justified, not only because the life habits of any insect, once ascertained, throw light on those of species which are closely related to it, but because we can never know when a species at present harmless may subsequently prove harmful, and have to be classed among the species injurious to agriculture.

On the question of credit to their original sources of results already on record, it is hardly necessary for me to advise, because good sense and the consensus of opinion will in the end justify or condemn a writer according as he prove just and conscientious in this regard.

There is one principle that should guide every careful writer, viz., that in any publications whatever, where facts or opinions are put forth, it should always be made clear as to which are based upon the author's personal experience and which are compiled or stated upon the authority of others. We should have no patience with a very common tendency to set forth facts, even those relating to the most common and best known species, without the indications to which I have referred. The tendency belittles our calling and is generally misleading and confusing, especially for bibliographic work, and cannot be too strongly deprecated.

On this point there will hardly be any difference of opinion, but I will allude to another question of credit upon which there prevails a good deal of loose opinion and custom. It is the habit of using illustrations of other authors without any indication of their original source.

This is an equally vicious custom and one to be condemned, though I know that some have fallen into the habit, without appreciation of its evil effect. It is, in my judgment, almost as blameworthy as to use the language or the facts of another without citing the authority.

Every member of this association who has due appreciation of the time and labor and special knowledge required to produce a good and true illustration of the transformations and chief characteristics of an insect will appreciate this criticism. However pardonable in fugitive newspaper articles in respect of cuts which, from repeated use, have become common or which have no individuality, the habit inevitably gives a certain spurious character to more serious and official publications, for assumption of originality, whether intended or not, goes with uncredited matter whether of text or figure. Nor is mere acknowledgment of loan or purchase to the publisher, institution or individual who may own the block or stone what I refer to. But that acknowledgment to the author of the figure or the work in which it first appears which is part of conscientious writing, and often a valuable index as to the reliability of the figure.

It were supererogation to point out to a body of this kind the value of the most careful and thorough work in connection with life histories and habits, often involving as it does much microscopic study of structure. The officers of our institutions who control the funds, and more or less fully our conduct, are apt to be somewhat impatient and inappreciative of the time given to anatomic work, and where it is given for the purpose of describing species and of synopsizing or monographing higher groups, without reference to agriculture, I am firmly of the belief that it diverts one from economic work, but where pursued for a definite economic purpose it cannot be too careful or too thorough and I know of no instances better calculated to appeal to and modify the views of those inclined to belittle such structural study than Phylloxera and Icerya. On the careful comparison of the European and American specimens of _Phylloxera vastatrix_, involving the most minute structures and details, depended originally those important economic questions which have resulted in legislation by many different nations and the regeneration of the affected vineyards of Europe, of our own Pacific coast, and of other parts of the world by the use of American resistant stocks. In the case of _Icerya purchasi_ the possibilities of success in checking it by its natural enemies hung at one time upon a question of specific difference between it and the _Icerya sacchari_ of Signoret--a question of minute structure which the descriptions left unsettled and which could only be settled by the most careful structural study and the comparison of the types, involving a trip to Europe.