Chapter XII: TECHNOLOGY.--Gaseous Illuminants.--By Prof. VIVIAN B (2)

The Empress of India is intended to be the pioneer of three fast mail steamers, built by the Barrow Shipbuilding Company for service in connection with the Canadian Pacific Railway, between Vancouver and the ports of China and Japan, thus forming the last link in the new route to the East through British territory. Her sister ships, the Empress of China and Empress of Japan, are to be ready in April next. These three ships all fulfill the requirements of the Board of Trade and of the Admiralty and Lloyd's, and are classed as 100 A1. They will also be placed on the list of British armed cruisers for service as commerce protectors in time of war. For this service each vessel is to be thoroughly fitted. There are two platforms forward and two aft, for mounting 7 in. Armstrong guns. These weapons, in the case of the Empress of India, are already awaiting the vessel at Vancouver. The Empress of India is painted white all over, has three pole masts to carry fore and aft sails. She has two buff-colored funnels and a clipper stern, and in external build much resembles the City of Rome. Her length over all is 485 feet; beam, 51 feet; depth, 36 feet; and gross tonnage, 5,920 tons. The hull, of steel, is divided into fifteen compartments by bulkheads, and has a cellular double bottom 4 feet in depth and 7 feet below the engine room. There are four complete decks. The ship is designed to carry 200 saloon passengers, 60 second cabin, and 500 steerage--these last chiefly Chinese coolies, for whose special delectation an "opium room" has been provided on board.--_Daily Graphic_.

* * * * *

CHICAGO AS A SEAPORT.

The prairie land in the southwest corner of Lake Michigan, which, seventy years ago, was half morass from the overflowing of the sluggish creek, whose waters, during flood, spread over the low-lying, level plain, or were supplemented in the dry season by the inflow from the lake, showed no sign of any future development and prosperity. The few streets of wooden houses that had been built by their handful of isolated inhabitants seemed likely rather to decay from neglect and desertion than to increase, and ultimately to be swept away by fire, to make room for the extravagant and gigantic buildings that to-day characterize American civilization and commercial prosperity. Nearly 1,000 miles from the Atlantic, a greater distance from the Gulf of Mexico, and 2,000 miles from the Pacific, no wilder dream could have been imagined fifty years ago than that Chicago should become a seaport, the volume of whose business should be second only to that of New York; that forty miles of wharves and docks lining the branches of the river should be insufficient for the wants of her commerce, and that none of the magnificent lake frontage could be spared to supply the demand.

Yet this is the situation to-day, the difficulties of which must increase many fold as years pass and business grows, unless some changes are made by which increased accommodation can be obtained. The nature of these changes has long engrossed the attention of the municipality and their engineers, and necessity is forcing them from discussion to action. As such action is likely to be taken soon, the subject is of sufficient interest to the English reader to devote some space to its consideration.

The most important problem, however, which the works to be undertaken--and which must of necessity be soon commenced--will have to solve, is not one of wharf accommodation or of increased facilities of commerce. It is the better disposal of the sewage of the city, the system in use at present being inadequate, and growing more and more imperfect as the city and its population increase. During the early days of Chicago, and indeed long after, the sewage question was treated with primitive simplicity, and with a complete disregard of sanitary laws.

The river and the lake in front of the city were close at hand and convenient to receive all the discharge from the drains that flowed into them. But this condition of things had to come to an end, for the lake supplied the population with water, and it became too contaminated for use. To obtain even this temporary relief involved much of the ground level of the city being raised to a height of 14 ft. above low water, a great undertaking carried out a number of years ago. To obtain an adequate supply of pure water, Mr. E.S. Chesborough, the city engineer, adopted the ingenious plan of driving a long tunnel beneath the bed of the lake, connected at the outer end to an inlet tower built in the water, and on shore to pumping engines. This plan proved so successful that it is now being repeated on a larger scale, and with a much longer tunnel, to meet the increased demands of the large population.

But to improve the sanitary condition of the city has been a much more difficult undertaking, as may be gathered from the following extract from an official report: "The present sanitary condition calls loudly for relief. The pollution of the Desplaines and the Illinois Rivers extends 81 miles, as far as the mouth of the Fox (see plan, Fig. 1) in summer low water, and occasionally to Peoria (158 miles) in winter. Outside of the direct circulation the river harbor is indescribable. The spewing of the harbor contents into the lake, the sewers constantly discharging therein, clouds the source of water supply (the lake) with contamination. Relief to Chicago and equity to her neighbors is a necessity of the early future." To make this quotation clear it is necessary to explain the actual condition of the Chicago sewage question.

Long before the present metropolis had arrived at the title and dignity of a city, the advantage to be derived from a waterway between Lake Michigan and the Illinois River, and thence to the Mississippi, was well understood. The scheme was, in fact, considered of sufficient importance to call for legislation as early as 1822, in which year an act was passed authorizing the construction of a canal having this object. It was not commenced, however, till 1836, and was opened to navigation in the spring of 1848. This canal extended from Chicago to La Salle, a distance of 97¼ miles, and it had a fall of 146 ft. to low water in the Illinois River (see Fig. 1). It was only a small affair, 6 ft. deep, and 60 ft. wide on the surface; the locks were 110 ft. long and 18 ft. wide. The summit level, which was only 8 ft. above the lake, was 21 miles in length. This limited waterway remained in use for a number of years, until, in fact, the growth of Chicago rendered it impossible to allow the sewage to flow any longer into the lake. In 1865 the State of Illinois sanctioned widening and lowering the canal so that it should flow by gravity from Lake Michigan. The enlargement was completed in 1871, by the city of Chicago, and the sewage was then discharged toward the Illinois River. But the flow was insufficient, and in 1881 the State called on the city to supplement the flow by pumping water into the canal.

In 1884, engines delivering 60,000 gallons a minute were set to work and remedied the evil for a time, so far as the city of Chicago was concerned, but the large discharge of sewage through the sluggish current of the canal and into the Illinois River proved a serious and ever-increasing nuisance to the inhabitants in the adjoining districts. To enlarge the existing canal, increase the volume and speed of its discharge, and to alter the levels, so that there shall be a relatively rapid stream flowing at all times from Lake Michigan, appears the only practical means of affording relief to the city, and immunity to other towns and villages lying along the route of the stream.

The physical nature of the country is well suited for carrying out such a project on a scale far larger than that required for sewage purposes, and works thus carried out would, to a small extent, restore the old water _regime_ in this part of the continent. Before the vast surface changes produced during the last glacial period, three of the great lakes--Michigan, Huron and Superior--discharged their waters southward into the Gulf of Mexico by a broad river. The accumulation of glacial debris changed all this; the southern outlet was cut off, and a new one to the north was opened near where Detroit stands, making a channel to Lake Erie, which then became the outlet for the whole chain by way of Niagara. A very slight change in levels would serve to restore the present _regime_. Around Lake Michigan the land has been slightly raised, the summit above mean water level being only about 8 ft. Thirty miles from the south shore the lake level is again reached at a point near Lockport (see Fig. 2); the fall then becomes more marked. At Lake Joliet, 10 miles further, the fall is 77 ft.; and at La Salle, 100 miles from Chicago, the total fall reaches 146 feet. At La Salle the Illinois River is met, and this stream, after a course of 225 miles, enters the Missouri. In the whole distance the Illinois River has a fall of 29 ft. "It has a sluggish current; an oozy bed and bars, formed chiefly by tributaries, with natural depths of 2 ft. to 4 ft.; banks half way to high waters, and low bottoms, one to six miles wide, bounded by terraces, overflowed during high water from 4 ft. to 12 ft. deep, and intersected in dry seasons by lake, bayou, lagoon, and marsh, the wreck of a mighty past."

The rectification of the Illinois and the construction of a large canal from La Salle to Lake Michigan are, therefore, all that is necessary to open a waterway to the Gulf of Mexico, and to make Chicago doubly a port; on the one hand, for the enormous lake traffic now existing; on the other, for the trade that would be created in both directions, northward to Lake Michigan, and southward to the Gulf.

As a matter of fact this great scheme has long occupied the attention of the United States government. A bill in 1882 authorized surveys for "a canal from a point on the Illinois River, at or near the town of Hennepin, by the most practical route to the Mississippi River ... and a survey of the Illinois and Michigan Canal connecting the Illinois River with Chicago, and estimates from its enlargements." This scheme only contemplated navigation for boats up to 600 tons. In 1885 the Citizens' Association, of Chicago caused a report to be made for an extended plan. The name of Mr. L.E. Cooly, at that time municipal sanitary engineer, was closely associated with this report, as it is at the present time for the agitation for carrying out the works. This report recommended that "an ample channel be created from Chicago to the Illinois River, sufficient to carry away in a diluted state the sewage of a large population. That this channel may be enlarged by the State or national government to any requirement of navigation or water supply for the whole river, creating incidentally a great water power in the Desplaines valley." Following this report and that of a Drainage and Water Supply Commission, a bill was introduced into Congress supporting the recommendations that had been made, and providing the financial machinery for carrying it into execution. Since that date much discussion has taken place, and some little action; meanwhile the sanitary requirements of the city are growing more urgent, and the pressure created from this cause will enforce some decision before long. Whether the new waterway is to be practically an open sewer or a ship canal remains yet to be seen, but it is tolerably certain that its dimensions and volume of water must approximate to the latter, if the large populations of other towns are to be satisfied. In fact the actual necessities are so great as regards sectional area of canal and flow of water--at least 600,000 ft. a minute--that comparatively small extra outlay would be needed to complete the ship canal.

The attention of engineers in Chicago, as well as of the United States government, is consequently closely directed at the present time to such a solution of the problem as shall secure to Chicago such a waterway as will dispose of the sewage question for very many years to come; that shall relieve the inhabitants on the line of the canal from all nuisances arising from the sewage disposal, and shall provide a navigable channel for vessels of deep draught. The maps, Figs. 1 and 2, give an idea of the most favored scheme--that of Mr. Cooley.

As will be seen, the canal commencing near the mouth of the Chicago River passes through a cut in the low ridge forming the summit level; then it runs to Lake Joliet, and through the valleys of the Desplaines and Illinois Rivers, to the Mississippi at Grafton, a distance of 325 miles. The elevations and distances of the principal points are as follows:

------------------------------+------------+-----------+-----------+ | | | | | | Low Water | | | Miles from |Level below| High Water| | Lake | Chicago | above Low | | Michigan. | Datum. | Water. | | | | | ------------------------------+------------+-----------+-----------+ | | | | | | ft. | ft. | Lake Michigan | | | 4.7 | Lake Joliet | 40 | 77 | 5 to 6 | Kankakee River | 51.30 | 93.70 | 18 to 20 | Morris | 61 | 100.3 | 21 | Marseilles | 77 | 102.8 | 4 to 5 | Ottawa | 84.5 | 132.1 | 26 | La Salle | 100.3 | 146.6 | 28 | Hennepin | 115.8 | 148.7 | 25 | Peoria | 161.4 | 151.3 | 21 | Mouth of the Illinois | 325 | 172.4 | 20 | | | | | ------------------------------+------------+-----------+-----------+

The project in contemplation provides that the depth of the canal as far as Lake Joliet (which is about six miles long) shall be not less than 22 ft., and on to La Salle not less than 14 ft. at first, with facilities to increase it to 22 ft. Beyond La Salle to the mouth of the Illinois, dredging and flushing by the large volume of water pouring in from Lake Michigan would make and maintain ultimately a similar depth.

As it appears recognized that the sewage channel of Chicago must be 15 ft. deep, and as provision is now being made all over the great lake system for vessels drawing 20 ft. of water, a comparatively small additional outlay would provide for a channel available for the largest lake vessels. It is claimed that by the co-operation of the Chicago municipality and the general government--the latter to advance a sum of not less than $50,000,000--a ship (and sanitary) canal 22 ft. deep could be made from the lake to Joliet, extended thence to Utica, 20 ft. deep, and from there to the Mississippi, 14 ft. deep.

That such a work would vastly enhance the commerce, not only of Chicago, but of the whole section of the country through which the canal would pass, admits of but little doubt, and probably the outlay would be justified by results similar to those achieved with other great canal works and rectified rivers in the United States.

The following figures, showing the tonnage carried in 1888-89, give some idea of the volumes of water-borne traffic in America:

Tons.
Detroit River 19,099,060
Erie Canal 5,370,369
Sault Ste. Marie 7,516,022
Welland Canal 828,271
St. Lawrence Canal 1,500,096
Mississippi to New Orleans 3,177,000
" below St. Louis 845,000
Ohio 2,236,917
Chicago Canal and lake 11,029,575

Except on the Mississippi, it may be reckoned that navigation is closed by ice during five months a year. It may be mentioned, by way of comparison, that the traffic on the Suez Canal during the year 1888-89 was 6,640,834 tons.

One very interesting point in connection with this work is the effect that the diversion of so large a body of water from the lakes will have upon their _regime_. At least 10,000 cubic feet a second would be taken from Lake Michigan and find its way into the Mississippi; this is approximately 4½ per cent. of the total amount that now passes through the St. Clair River and thence over Niagara.

The following table gives some particulars of the great lakes and the discharge from them:

---------------+----------+-------+--------+-----------------------
| | | |Cubic Feet per Second.
|Elevation |Area of| Area of+-------+-------+-------
| above | Basin,| Lake, | | |
Lake. |Mean Tide.| Square| Square| Rain- |Evapo- | Dis-
| Feet. | Miles.| Miles.| fall. |ration.|charge.
| | | | | |
---------------+----------+-------+--------+-------+-------+-------
| | | | | |
Superior | 601.78 | 90,505| 38,875 |187,386| 34,495| 80,870
Huron and Mich.| 581.28 |121,941| 50,400 |262,964| 66,754|216,435
Erie | 572.86 | 40,298| 10,000 | 96,654| 13,870|235,578
Ontario | 246.61 | 31,558| 7,220 | 75,692| 10,568|272,095
| | | | | |
---------------+----------+-------+--------+-------+-------+-------

The average variation in level of the lakes is from 18 in. to 24 in. during the year, and the range in evaporation from year to year is also very considerable; thus the evaporation per second on Huron and Michigan, as given in the table above, is nearly 67,000 ft., but the figures for another year show nearly 89,000 ft. per second, which would represent a difference of 6½ in. in water level. As a discharge of 10,000 cubic feet a second into the new canal would lower the level of these two lakes by 2.87 in. in a year, it follows that the difference between a year of maximum and one of minimum evaporation is more than twice as great as would be required for the canal, and even under the most unfavorable conditions the volume taken from the whole chain of lakes would not lower them an inch.

When the variations in level due to different causes--rain, wind, and evaporation being the chief--are taken into consideration, the effect of 10,000 cubic feet a second abstracted would probably not be noticeable. That this would be so is the opinion, after careful investigation, of many eminent American engineers. On the other hand there is a similar unanimity of opinion as to the advantages that would be obtained in the condition of the Mississippi by adding to it a tributary of such importance as the proposed canal.--_Engineering_.

* * * * *

N.F. BURNHAM AND HIS LIFE WORK.

By W.H. BURNHAM.

The inventor and patentee of all water wheels known as the Burham turbine died from Bright's disease of the kidneys at his home, York, Pa., Dec. 22, 1890, aged 68 years 9 months and 9 days. He was born in the city of New York, March 13, 1822, and was of English-Irish and French descent. His father was a millwright and with him worked at the trade in Orange county, N.Y., until he was 16 years old. He then commenced learning the watchmakers' business, which he was obliged to relinquish, after three years, on account of his health. He then went to Laurel, Md., in 1844, and engaged with Patuxent & Co. as mercantile clerk and bookkeeper. In 1856 he commenced the manufacture of the French turbine water wheel. In 1879 he sold out his Laurel interests, went to New York and commenced manufacturing his own patents. On May 22, 1883, he founded the Drovers' and Mechanics' National Bank of York, and was elected its first president, which position he held at the time of his death. In 1881, with others, he built the York opera house, at a cost of $40,000. He was a Knight Templar, and past master of the I.O.O.F., and past sachem of Red Men.

He was the oldest turbine wheel manufacturer living, having been actually engaged in the manufacture of turbines since 1856. He first made and sold the French Jonval turbine, which was then the best turbine made, but being complicated in construction, it soon wore out and leaked. From the experience he had from this wheel he invented and patented Feb. 22, 1859, his improved Jonval turbine, which was very simply constructed and yielded a greater percentage of power than the French Jonval turbines. Hundreds of these improved wheels, which were put in operation between the years 1859 and 1868, are still in use. (We show no cut of this wheel, but it had four chutes instead of six, as shown in March 24, 1863, patent.)

The first wheel (72 inch) made after the patent was granted was sold to Brightwell & Davis, Farmville, Va., and put into their flour mill under six feet head. In 1870, Brightwell & Davis sold their mill to Scott & Davis. Afterward G.W. Davis owned and operated the mill and put in one 1858 patent "New Turbine." In 1889 the Farmville Mill Company bought and remodeled the mill to roller process and required more power than the old 1856 Jonval turbine and 1868 "New Turbine" would yield, and on Aug. 30, 1889, sold the Farmville Mill Company two 54 inch new improved Standard turbines to displace the two old wheels. In 1860 he commenced experimenting with different forms of buckets and chutes, and used six chutes instead of four as first made, and was granted patent March 24, 1863.

This addition of chutes proved beneficial, as the wheel worked better with the gates partly opened than it did with four chutes. His next invention was granted him Dec. 24, 1867, which he called Burnham's improved central and vertical discharge turbine.

This improvement consisted in making the guide blade straight on the outside (instead of rounding, as then made by all others), from inner point back to bolt or gudgeon, and thick enough at the latter point to let water pass without being obstructed by said bolt and the arrangement for shifting the water guides. Two 42-inch wheels of this pattern were built and put into operation, but they soon commenced leaking water and became troublesome on account of the many small pieces of castings and bolts, and were abandoned as worthless. There are several manufacturers of this style of wheel that advertise them as "simple and durable." Such a complicated case with twelve chutes cannot be made to operate unless by a large number of castings, bolts and studs. With these adjustable water guides, one of the objects was obtained. Admitting the water to the wheel through chutes corresponding in height to the outer edge of buckets exposed, but not placing the water against the face of the buckets at right angles with the center of the wheel, except when the guide blades were full opened, for as the guides are changed so is the current of the water likewise changed.

After making several differently constructed wheels and testing them a number of times, he selected the best one and obtained a patent for it March 3, 1868, and called it "new turbine," which he still further improved and patented May 9, 1871. This "new turbine" consisted of the former improved Jonval wheel, hub and buckets, with a new circular case and new form of chutes, having a register gate entirely surrounding the case and having apertures corresponding to those in the case for admitting water to the wheel. This register gate was moved by means of a segment and pinion.

This "new turbine" soon gained for itself a reputation enjoyed by no other water wheel. It was selected by the United States Patent Office, and put at work in room 189, to run a pump which forces water to the top of the building. It was likewise selected by the Japan commission when they were in this country to select samples of our best machines. He continued making the 1868 patent and improved in 1871 "new turbine" but a few years, for as long as he could detect a defect in the wheel, case or gate, he continued improving and simplifying them, and in 1873 he erected a very complete testing flume, also made a very sensitive dynamometer, it having a combination screw for tightening the friction band, which required 100 turns to make one inch, and commenced making and experimenting with different constructed turbines. He made five different wheels and made over a hundred tests before he was satisfied. Application was then made for a patent, which was granted March 31, 1874, for his "Standard turbine."

This "Standard turbine" was a combination of his former improvements, with the cover extending over top of the gate to prevent it from tilting, and an eccentric wheel working in cam yoke to open and close the gate.

Thousands of Standard turbines are to-day working and giving the best satisfaction, and we venture to say that not one of the Standard turbines has been displaced by any other make of turbine, which gave better results for the water used. In 1881 he again commenced experimenting to find out how much water could be put through a wheel of given diameter. After making and testing several wheels it was found that the amount of water with full gate drawn named in tables found in Burnham Bros.' latest catalogue for each size wheel yielded 84 per cent. and that the water used with 7/8 gate drawn yielded the same percentage (84), or with 3/4 gate 82 per cent., 5/8 gate 79, and 1/2 gate 75 per cent. A patent for the mechanism was applied for and granted March 27, 1883, and named Burnham's Improved Standard Turbine.

It was found that the brackets with brass rollers attached, to prevent the gate from rising and tilting and rubbing the curb, soon wore and allowed the gate to rub against the curb, and he experimented with several devices of gate arms. While so engaged he found that the great weight of water on the top of the cover sprang it, causing the sleeve bearing on the under side of the cover to be thrown out of place, and the gate pressed so hard against the case that it was almost impossible to move it, and after thoroughly testing with the different devices of gate arms, application was made and patent granted for adjustable gate arms, also for the new worm gate gearing May 1, 1888, and named Burham's new improved standard turbine.

This he improved and patented May 13, 1890, to run on horizontal shaft.

In the year 1872 he had two patents granted him for improvement in water wheels, but never had any wheels built of that pattern. After completing and patents granted for his new improved Standard turbine, he was perfectly satisfied, and often remarked, "I cannot improve on my register gate turbine any more, as it is as near perfection as can be made," and he was fully convinced, for the past year he was experimenting with a cylinder gate turbine, and patent was granted Oct. 21, 1890. Previously he had made a 24-inch wheel, which was tested Aug. 14, 1890, at Holyoke testing flume, and gave fair results, and at the time of his demise he was having made a new runner for the cylinder gate turbine, which we will complete and have tested. His idea was to have us manufacture and sell register and cylinder gate turbines. His inventive powers were not confined to water wheels, for on Feb. 23, 1886, patents were granted him for automatic steam engine, governor and lubricating device. We also remember in the year 1873 or 1874, when his mind was occupied with his "Standard turbine," he was hindered by some device used now on locomotives of the present construction (what it was we are unable to say), but when draughting at his water wheel, would conflict the two, and by his invitation we wrote to a prominent locomotive builder and had him examine the drawings, which he had not fully completed, and sold same to him. Of this we only have a faint recollection, but do recollect his saying: "Well, that is off my mind now, and I can devote it to the finishing of my new wheel."--_American Miller_.

* * * * *

ALTERNATE CURRENT CONDENSERS.

At a recent meeting of the Physical Society, London, Mr. James Swinburne read a paper on alternate current condensers. It is, he said, generally assumed that there is no difficulty in making commercial condensers for high pressure alternating currents. The first difficulty is insulation, for the dielectric must be very thin, else the volume of the condenser is too great. Some dielectrics 0.2 mm. thick can be made to stand up to 8,000 volts when in small pieces, but in complete condensers a much greater margin must be allowed. Another difficulty arises from absorption, and whenever this occurs, the apparent capacity is greater than the calculated. Supposing the fibers of paper in a paper condenser to be conductors embedded in insulating hydrocarbon, then every time the condenser is charged the fibers have their ends at different potentials, so a current passes to equalize them and energy is lost. This current increases the capacity. One condenser made of paper boiled in ozokerite took an abnormally large current and heated rapidly. At a high temperature it gave off water, and the power wasted and current taken gradually decreased.

When a thin plate of mica is put between tin foils, it heats excessively; and the fall of potential over the air films separating the mica and foil is great enough to cause disruptive discharge to the surface of the mica. There appears to be a luminous layer of minute sparks under the foils, and there is a strong smell of ozone. In a dielectric which heats, there may be three kinds of conduction, viz., metallic, when an ordinary conductor is embedded in an insulator; disruptive, as probably occurs in the case of mica; and electrolytic, which might occur in glass. In a transparent dielectric the conduction must be either electrolytic or disruptive, otherwise light vibrations would be damped. The dielectric loss in a cable may be serious. Calculating from the waste in a condenser made of paper soaked in hot ozokerite, the loss in one of the Deptford mains came out 7,000 watts. Another effect observed at Deptford is a rise of pressure in the mains. There is as yet no authoritative statement as to exactly what happens, and it is generally assumed that the effect depends on the relation of capacity to self-induction, and is a sort of resonator action. This would need a large self-induction, and a small change of speed would stop the effect. The following explanation is suggested. When a condenser is put on a dynamo, the condenser current leads relatively to the electromotive force, and therefore strengthens the field magnets and increases the pressure.

In order to test this, the following experiment was made for the author by Mr. W.F. Bourne. A Gramme alternator was coupled to the low pressure coil of a transformer, and a hot wire voltmeter put across the primary circuit. On putting a condenser on the high pressure circuit, the voltmeter wire fused. The possibility of making an alternator excite itself like a series machine, by putting a condenser on it, was pointed out. Prof. Perry said it would seem possible to obtain energy from an alternator without exciting the magnets independently, the field being altogether due to the armature currents. Mr. Swinburne remarked that this could be done by making the rotating magnets a star-shaped mass of iron. Sir W. Thomson thought Mr. Swinburne's estimate of the loss in the Deptford mains was rather high. He himself had calculated the power spent in charging them, and found it to be about 16 horse power, and although a considerable fraction might be lost, it would not amount to nine-sixteenths. He was surprised to hear that glass condensers heated, and inquired whether this heating was due to flashes passing between the foil and the glass. Mr. A.P. Trotter said Mr. Ferranti informed him that the capacity of his mains was about 1/3 microfarad per mile, thus making 2-1/3 microfarads for the seven miles. The heaping up of the potential only took place when transformers were used, and not when the dynamos were connected direct. In the former case the increase of volts was proportional to the length of main used, and 8,500 at Deptford gave 10,000 at London.

Mr. Blakesley described a simple method of determining the loss of power in a condenser by the use of three electrodynamometers, one of which has its coils separate. Of these coils, one is put in the condenser circuit, and the other in series with a non-inductive resistance r, shutting the condenser. If a_{2} be the reading of a dynamometer in the shunt circuit, and a_{3} that of the divided dynamometer, the power lost is given by r (Ca_{3} - Ba_{2}) where B and C are the constants of the instruments on which a_{2} and a_{3} are the respective readings. Prof. S.P. Thompson asked if Mr. Swinburne had found any dielectric which had no absorption. So far as he was aware, pure quartz crystal was the only substance. Prof. Forbes said Dr. Hopkinson had found a glass which showed none. Sir William Thomson, referring to the same subject, said that many years ago he made some tests on glass bottles, which showed no appreciable absorption. Sulphuric acid was used for the coatings, and he found them to be completely discharged by an instantaneous contact of two balls. The duration of contact would, according to some remarkable mathematical work done by Hertz in 1882, be about 0.0004 second, and even this short time sufficed to discharge them completely.

On the other hand, Leyden jars with tinfoil coatings showed considerable absorption, and this he thought due to want of close contact between the foil and the glass. To test this he suggested that mercury coatings be tried. Mr. Kapp considered the loss of power in condensers due to two causes: first, that due to the charge soaking in; and second, to imperfect elasticity of the dielectric. Speaking of the extraordinary rise of pressure on the Deptford mains, he said he had observed similar effects with other cables. In his experiments the sparking distance of a 14,000 volt transformer was increased from 3/16 of an inch to 1 inch by connecting the cables to its terminals. No difference was detected between the sparking distances at the two ends of the cable, nor was any rise of pressure observed when the cables were joined direct on the dynamo.

In his opinion the rise was due to some kind of resonance, and would be a maximum for some particular frequency. Mr. Mordey mentioned a peculiar phenomenon observed in the manufacture of his alternators. Each coil, he said, was tested to double the pressure of the completed dynamo, but when they were all fitted together, their insulation broke down at the same volts. The difficulty had been overcome by making the separate coils to stand much higher pressures. Prof. Rucker called attention to the fact that dielectrics alter in volume under electric stress, and said that if the material was imperfectly elastic, some loss would result. The president said that, as some doubt existed as to what Mr. Ferranti had actually observed, he would illustrate the arrangements by a diagram. Speaking of condensers, he said he had recently tried lead plates in water to get large capacities, but so far had not been successful.

Mr. Swinburne, in replying, said he had not made a perfect condenser yet, for, although he had some which did not heat much, they made a great noise. He did not see how the rise of pressure observed by Mr. Ferranti and Mr. Kapp could be due to resonance. Mr. Kapp's experiment was not conclusive, for the length of spark is not an accurate measure of electromotive force. As regards Mr. Mordey's observation, he thought the action explicable on the theory of the leading condenser current acting on the field magnets. The same explanation is also applicable to the Deptford case, for when the dynamo is direct on, the condenser current is about 10 amperes, and this exerts only a small influence on the strongly magnetized magnets. When transformers are used, the field magnets are weak, while the condenser current rises to 40 amperes. Mr. Blakesley's method of determining losses was, he said, inapplicable except where the currents were sine functions of the time; and consequently could not be used to determine loss due to hysteresis in iron, or in a transparent dielectric.--_Nature._

* * * * *

THE TELEGRAPHIC COMMUNICATION BETWEEN GREAT BRITAIN, EUROPE, AMERICA, AND THE EAST.

By GEORGE WALTER NIVEN.

There are at present twenty-six submarine cable companies, the combined capital of which is about forty million pounds sterling. Their revenue, including subsidies, amounts to 3,204,060£.; and their reserves and sinking funds to 3,610,000£.; and their dividends are from one to 14¾ per cent. The receipts from the Atlantic cables alone amount to about 800,000£. annually.

The number of cables laid down throughout the world is 1,045, of which 798 belong to governments and 247 to private companies. The total length of those cables is 120,070 nautical miles, of which 107,546 are owned by private telegraph companies, nearly all British; the remainder, or 12,524 miles, are owned by governments.

The largest telegraphic organization in the world is that of the Eastern Telegraphic Company, with seventy cables, of a total length of 21,859 nautical miles. The second largest is the Eastern Extension, Australasia and China Telegraph Company, with twenty-two cables, of a total length of 12,958 nautical miles. The Eastern Company work all the cables on the way to Bombay, and the Eastern Extension Company from Madras eastward. The cables landing in Japan, however, are owned by a Danish company, the Great Northern. The English station of the Eastern Company is at Porthcurno, Cornwall, and through it pass most of the messages for Spain, Portugal, Egypt, India, China, Japan, and Australia.

The third largest cable company is the Anglo-American Telegraph Company, with thirteen cables, of a total length of 10,196 miles.

The British government has one hundred and three cables around our shores, of a total length of 1,489 miles. If we include India and the colonies, the British empire owns altogether two hundred and sixteen cables of a total length of 3,811 miles.

The longest government cable in British waters is that from Sinclair Bay, Wick, to Sandwick Bay, Shetland, of the length of 122 miles, and laid in 1885. The shortest being four cables across the Gloucester and Sharpness Canal, at the latter place, and each less than 300 ft. in length.

Of government cables the greatest number is owned by Norway, with two hundred and thirty-six, averaging, however, less than a mile each in length.

The greatest mileage is owned by the government of France with 3,269 miles, of the total length of fifty-one cables.

The next being British India with 1,714 miles, and eighty-nine cables; and Germany third with 1,570 miles and forty-three cables.

Britain being fourth with ninety miles less. The oldest cable still in use is the one that was first laid, that namely from Dover to Calais. It dates from 1851.

The two next oldest cables in use being those respectively from Ramsgate to Ostend, and St. Petersburg to Cronstadt, and both laid down in 1853.

Several unsuccessful attempts were made to connect England and Ireland by means of a cable between Holyhead and Howth; but communication between the two countries was finally effected in 1853, when a cable was successfully laid between Portpatrick and Donaghadee (31).

As showing one of the dangers to which cables laid in comparatively shallow waters are exposed, we may relate the curious accident that befell the Portpatrick cable in 1873. During a severe storm in that year the Port Glasgow ship Marseilles capsized in the vicinity of Portpatrick, the anchor fell out and caught on to the telegraph cable, which, however, gave way. The ship was afterward captured and towed into Rothesay Bay, in an inverted position, by a Greenock tug, when part of the cable was found entangled about the anchor.

The smallest private companies are the Indo-European Telegraph Company, with two cables in the Crimea, of a total length of fourteen and a half miles; and the River Plate Telegraph Company, with one cable from Montevideo to Buenos Ayres, thirty-two miles long.

The smallest government telegraph organization is that of New Caledonia, with its one solitary cable one mile long.

We will now proceed to give a few particulars regarding the companies having cables from Europe to America.

The most important company is the Anglo-American Telegraph Company, whose history is inseparably connected with that of the trials and struggles of the pioneers of cable laying.

Its history begins in 1851 when Tebets, an American, and Gisborne, an English engineer, formed the Electric Telegraph Company of Newfoundland, and laid down twelve miles of cable between Cape Breton and Nova Scotia. This company was shortly afterward dissolved, and its property transferred to the Telegraphic Company of New York, Newfoundland and London, founded by Cyrus W. Field, and who in 1854 obtained an extension of the monopoly from the government to lay cables.

A cable, eighty-five miles long, was laid between Cape Breton and Newfoundland (22).

Field then came to England and floated an English company, which amalgamated with the American one under the title of the Atlantic Telegraph Company.

The story of the laying of the Atlantic cables of 1857 and 1865, their success and failures, has often been told, so we need not go into any details. It may be noted, however, that communication was first established between Valentia and Newfoundland on August 5. 1858, but the cable ceased to transmit signals on September 1, following.

During that period, ninety-seven messages had been sent from Valentia, and two hundred and sixty-nine from Newfoundland. At the present time, the ten Atlantic cables now convey about ten thousand messages daily between the two continents. The losses attending the laying of the 1865 cable resulted in the financial ruin of the Atlantic company and its amalgamation with the Anglo-American. In 1866 the Great Eastern successfully laid the first cable for the new company, and with the assistance of other vessels succeeded in picking up the broken end of the 1865 cable and completing its connection with Newfoundland.

Reference to places--A, Heart's Content; B, Placentia; C, St. Peter Miquelon; D, North Sydney, Cape Breton Island; E, Louisbourg; F Canso, Nova Scotia; G, Halifax; H, Bird Rock; I, Madeline Isles; J, Anticosti; K, Charlotte Town, Prince Edward's Island; LLL, Banks of Newfoundland.]

The three cables of this company presently in use and connecting Valentia in Ireland with Heart's Content in Newfoundland, were laid in 1873, 1874, and 1880; and (1) are respectively 1886, 1846, and 1890 nautical miles in length. This company also owns the longest cable in the world, that namely from Brest in France to St. Pierre Miquelon, one of a small group of islands off the south coast of Newfoundland and which, strange to say, still belongs to France (6).

The length of this cable is 2,685 nautical miles, or 3,092 statute miles. It was laid in 1869. There are seven cables of a total length of 1773 miles, connecting Heart's Content, Placentia Bay and St. Pierre, with North Sydney, Nova Scotia, and Duxbury, near Boston, belonging to the American company. Communication is maintained with Germany and the rest of the Continent by means of a cable from Valentia to Emden 846 miles long (7); and a cable from Brest to Salcombe, Devon, connects the St. Pierre and Brest cable with the London office of the company (10).[1]

[Footnote 1: Cables not fully described in the text, Map B. Eight cables at the Anglo-American Company: 7, Heart's Content to Placentia, two cables; 8, Placentia to St. Pierre; 9, St. Pierre to North Sydney; 10, Placentia to North Sydney, two cables; 11, St. Pierre to Duxbury; 18, Charlotte's Town to Nova Scotia; 19, Government Cable, North Sydney to Bird Rock, Madeline Isles, and Anticosti; 21, Halifax and Bermuda Cable Company's proposed cable to Bermuda.]

The station of the Direct United States Cable Company is situated at Ballinskelligs Bay, Ireland (2). Its cable was laid in 1874-5, and is 2,565 miles in length. The terminal point on the other side of the Atlantic is at Halifax, Nova Scotia, from whence the cable is continued to Rye Beach, New Hampshire, a distance of 536 miles, and thence by a land line of 500 miles to New York (17).

The Commercial Cable Company's station in Ireland is at Waterville, a short distance from Ballinskelligs (3). It owns two cables laid in 1885; the northern cable being 2,350, and the southern 2,388 miles long. They terminate in America at Canso, Nova Scotia. From Canso a cable is laid to Rockfort, about thirty miles south of Boston, Mass., a distance of 518 miles (16), and another is laid to New York, 840 miles in length (15). This company has direct communication with the Continent by means of a cable from Waterville to Havre of 510 miles (9), and with England by a cable to Weston-super-Mare, near Bristol, of 328 miles (8).

The Western Union Telegraph Company (the lessees of the lines of the American Telegraph and Cable Company) has two cables from Sennen Cove, Land's End, to Canso, Nova Scotia (4). The cable of 1881 is 2,531 and that of 1882 is 2,576 miles in length. Two cables were laid November, 1889, between Canso and New York (14).

The Compagnie Française du Telegraphe de Paris à New York has a cable from Brest to St. Pierre Miquelon of 2,242 miles in length (5), from thence a cable is laid to Louisbourg, Cape Breton (12), and another to Cape Cod (13). It has also a cable from Brest to Porcella Cove, Cornwall (11).

Those ten cables owned by the six companies named, of the total milage of 22,959, not counting connections, represent the entire direct communication between the continents of Europe and North America.

A new company, not included in the preceding statistics, proposes to lay a cable from Westport, Ireland, to some point in the Straits of Belle Isle on the Labrador coast (Map A32, Map B20).

The station of the Eastern Telegraph Company is at Porthcurno Cove, Penzance, from whence it has two cables to Lisbon, one laid in 1880, 850 miles long, the other laid in 1887, 892 miles long (12), and one cable to Vigo, Spain, laid in 1873, 622 miles long (13). From Lisbon the cable is continued to Gibraltar and the East, whither we need not follow it, our intention being to confine ourselves entirely to a brief account of those cables communicating directly with Europe and America. As already stated, this company has altogether seventy cables, of a total length of nearly 22,000 miles.

The Direct Spanish Telegraph Company has a cable, laid in 1884, from Kennach Cove, Cornwall, to Bilbao, Spain, 486 miles in length (14).

Coming now to shorter cables connecting Britain with the Continent, we have those of the Great Northern Telegraph Company, namely, Peterhead to Ekersund, Norway, 267 miles (15). Newbiggin, near Newcastle, to Arendal, Norway, 424 miles, and thence to Marstrand, Sweden, 98 miles.

Two cables from the same place in England to Denmark (Hirstals and Sondervig) of 420 and 337 miles respectively (17 and 18).

The great Northern Company has altogether twenty-two cables, of a total length of 6,110 miles. The line from Newcastle, is worked direct to Nylstud, in Russia--a distance of 890 miles--by means of a "relay" or "repeater," at Gothenburg. The relay is the apparatus at which the Newcastle current terminates, but in ending there it itself starts a fresh current on to Russia.

The other continental connections belong to the government, and are as follows: two cables to Germany, Lowestoft to Norderney, 232 miles, and to Emden, 226 miles (19 and 20).

Two cables to Holland: Lowestoft to Zandvoort, laid in 1858 (21), and from Benacre, Kessingland, to Zandvoort (22).

Two cables to Belgium: Ramsgate to Ostend (23), and Dover to Furness (24).

Four cables to France: Dover to Calais, laid in 1851 (25), and to Boulogne (26), laid in 1859; Beachy Head to Dieppe (27), and to Havre (28).

There is a cable from the Dorset coast to Alderney and Guernsey, and from the Devon coast to Guernsey, Jersey, and Coutances, France (29 and 30).

A word now as to the instruments used for the transmission of messages. Those for cables are of two kinds, the mirror galvanometer and the siphon recorder, both the product of Sir Wm. Thomson's great inventive genius.

When the Calais-Dover and other short cables were first worked, it was found that the ordinary needle instrument in use on land lines was not sufficiently sensitive to be affected trustworthily by the ordinary current it was possible to send through a cable. Either the current must be increased in strength or the instruments used must be more sensitive. The latter alternative was chosen, and the mirror galvanometer was the result.

The principle on which this instrument works may be briefly described thus: the transmitted current of electricity causes the deflection of a small magnet, to which is attached a mirror about three-eighths of an inch in diameter, a beam of light is reflected from a properly arranged lamp, by the mirror, on to a paper scale. The dots and dashes of the Morse code are indicated by the motions of the spot of light to the right and left respectively of the center of the scale.

The mirror galvanometer is now almost entirely superseded by the siphon recorder. This is a somewhat complicated apparatus, with the details of which we need not trouble our readers. Suffice it for us to explain that a suspended coil is made to communicate its motions, by means of fine silk fibers, to a very fine glass siphon, one end of which dips into an insulated metallic vessel containing ink, while the other extremity rests, when no current is passing, just over the center of a paper ribbon. When the instrument is in use the ink is driven out of the siphon in small drops by means of an electrical arrangement, and the ribbon underneath is at the same time caused to pass underneath its point by means of clockwork.

If a current be now sent through the line, the siphon will move above or below the central line, thus giving a permanent record of the message, which the mirror instrument does not. The waves written by the siphon above the central line corresponding to the dots of the Morse code, and the waves underneath corresponding to the dashes.

The cost of the transmission of a cablegram varies from one shilling per word, the rate to New York and east of the Mississippi, to ten shillings and seven pence per word, the rate to New Zealand. In order to minimize that cost as much as possible, the use of codes, whereby one word is made to do duty for a lengthy phrase, is much resorted to. Of course those code messages form a series of words having no apparent relation to each other, but occasionally queer sentences result from the chance grouping of the code words. Thus a certain tea firm was once astonished to receive from its agent abroad the startling code message--"Unboiled babies detested"!

Suppose we now follow the adventures of a few cablegrams in their travels over the world.

A message to India from London by the cable route requires to be transmitted eight times at the following places: Porthcurno (Cornwall), Lisbon, Gibraltar, Malta, Alexandria, Suez, Aden, Bombay.

A message to Australia has thirteen stoppages; the route taken beyond Bombay being via Madras, Penang, Singapore, Banjoewangie and Port Darwin (North Australia); or from Banjoewangie to Roebuck Bay (Western Australia).

To India by the Indo-European land lines, messages go through Emden, Warsaw, Odessa, Kertch, Tiflis, Teheran, Bushire (Persian Gulf), Jask and Kurrachee, but only stop twice between London and Teheran--namely, at Emden and Odessa.

Messages from London to New York are transmitted only twice--at the Irish or Cornwall stations, and at the stations in Canada. Owing to the great competition for the American traffic, the service between London, Liverpool, and Glasgow and New York is said to be much superior to that between any two towns in Britain. The cables are extensively used by stock brokers, and it is a common occurrence for one to send a message and receive a reply within five minutes.

During breakages in cables messages have sometimes to take very circuitous routes. For instance, during the two days, three years ago, that a tremendous storm committed such havoc among the telegraph wires around London, cutting off all communication with the lines connected with the Channel cables at Dover, Lowestoft, etc., it was of common occurrence for London merchants to communicate with Paris through New York. The cablegram leaving London going north to Holyhead and Ireland, across the Atlantic to New York and back _via_ St. Pierre to Brest and thence on to Paris, a total distance of about seven thousand miles.

Three years ago, when the great blizzard cut off all communication between New York and Boston, messages were accepted in New York, sent to this country, and thence back to Boston.