be sunk quite below the terreplein for protection. This great depth, of course, necessitates some method of raising the powder charges to the platform level. Devices to that end have been worked out in connection with new plans for magazines, and drawings thereof prepared. They are not, however, forwarded, as the investigation of this subject and the results obtained are not as yet regarded as final.

Torpedo defense.-The annual appropriation ($50,000) made for the fiscal year 1881-'82 for providing materials to defend our coasts with submarine mines and for continuing trials to perfect the system was allotted, upon the recommendation of this board, chiefly to the purchase of torpedo cases and junction boxes, to be stored for use in the channels leading to Philadelphia and Boston. These cities and New York are now provided with a minimum supply of the parts which would be most difficult to procure in haste, but nothing has been done for any other of our great sea-ports. The materials are not liable to deteriorate in store, and not less than $100,000 should be expended annually for several years to come in providing these most necessary supplies.

The debate in Congress upon the bill making provision for the current year renders it evident that the vast importance of preparing our forts for successfully operating and defending the torpedoes was not understood. Without such preparation it would be of little use to have them in readiness. They are all controlled by electricity. To convey the electrical current, insulated wires must extend from a secure bomb-proof to each torpedo. If these wires are not buried so deeply in the earth as to be out of the reach of hostile artillery fire, a single lucky shot may destroy the power of exploding all the mines, and hence may open the channel to the enemy. Very few of our forts are provided with these bomb-proof operating-rooms and cable shafts and galleries, and a special appropriation is required for constructing them. After the breaking out of war the needful time would be lacking, and this matter cannot be urged in too strong language. The cost will be small-probably $200,000 would cover the more important stations on the Atlantic coastand it is recommended that a special item for this purpose be inserted in the bill for the coming year. These preparations are as necessary to our torpedoes as triggers are to our rifled muskets; in fact, they perform a like function.

Before any reasonable expectation of successfully defending our coast with torpedoes can be entertained, another matter should receive attention. Torpedoes will not plant and operate themselves. This must be done by soldiers specially trained in the use of electricity and instructed in certain difficult and delicate mechanical operations. In every nation this duty is devolved upon the engineer troops, and Congress has made the same provision for our service. The battalion organization provided by law is sufficient for the purpose; but the restriction of the total enlisted force of the Army to 25,000 men, and the pressing need of troops to perform police duty among the Indians on the plains, have so reduced the authorized strength of the battalion that only about 100 men are under instruction for defending our whole sea-coast and lake frontier. This difficulty is best met by the plan suggested by the General of the Army in 1879, viz, to place the Engineer troops upon the same footing as to recruiting as the Signal Service men. The latter are not included in the 25,000 men to which the strength of the Army is restricted by law. A provision to this effect would allow the President to recruit the battalion to a maximum strength of 752 men, which would be sufficient for present needs. These men are excellent soldiers, thoroughly instructed and disciplined, and inferior to no others in the serv

In the competition last year for the Nevada trophy, offered for excellence in markmanship, and open to the entire Army, one of the Engineer companies took the second place. These troops are as available as any others for use as infantry in any sudden emergency, while their special training and knowledge as the Torpedo Corps of the Army would make them of inestimable value should our coasts be attacked by a maritime power. This increase would be restricted entirely to enlisted men, and would involve an expense insignificant in proportion to the interests involved.

The investigations connected with the subject of torpedo defense have been continued at Willets Point by Lieutenant-Colonel Abbot, as heretofore.

The most laborious work has been the continuation of the study of the principles involved in the working of Sims' electrical fish torpedo, which includes the whole subject of electrical transmission of power. All needful appliances have been provided for measuring the work applied to the armature shaft of the dynamo machine, the work returned by the motor, the current generated under varying conditions of the latter as to speed, the constants of the dynamo (Weston No. 5), and of the motor, and many other matters tending to throw light upon the subject, and to indicate in what direction improvement can most judiciously be sought. Seventy elaborate dock trials and three runs of the fish were made during the working season of 1881. The various improvements suggested have been introduced into the machine during the past winter, and will soon be subjected to a new set of tests. As heretofore, the general result has been to confirm the good opinion already formed of this invention, and to strengthen the belief that it admits of being developed into an effective auxiliary to our system of channel-obstruction torpedoes.

Experiments upon a large scale have been carried out with a grand group of torpedoes planted in the channel off Willets Point in last October, and subjected to daily tests since that date. This work still continues, and can hardly fail to yield useful information of a practical character. An improved pattern of cut-off box has been devised and perfected during the winter.

In the matter of explosives less has been accomplished than usual. Some preliminary trials with a new variety-Rock-a-rock-have been made, and will be completed during the summer. A supply of tonite has been procured from California (two varieties), and is awaiting test. The Giant Powder Company, although holding the patents for explosive gelatine, has failed as yet to place it on the market, and has thus delayed a set of trials very important for our purposes. It may be remarked that a small sample, about a year old, underwent marked deterioration at Willets Point last winter, thus suggesting a new subject for study in connection with that explosive.

In the matter of insulated torpedo cable, much work has been done. The old samples purchased at various dates, beginning in 1873, with a view to try their endurance under wet and dry storage, have all been carefully tested and the conclusions formulated. Two miles of single conductor insulated with the latest dielectric, ozo-kerited India rubber, have been imported from England and subjected to the usual tests; thus far with very promising results. A single mile of wire insulated with vulcanized India rubber by a new American firm in Bristol, Pa., has also been placed under test.

Various new electrical apparatus, such as a sample Fauré battery, an Ayrton & Perry galvanometer, &c., have been procured for labora

tory trials; and a new portable machine for firing mines, put on the market by Laflin & Rand under the name of Magneto No. 4, has been carefully tested. It is a more powerful machine than their No. 3, requiring both hands to operate. Its equation appears to be the following, in which C denotes the instantaneous firing current, and R,, the exterior resistance. It will explode about twenty of our service fuses in series with certainty, and is worthy of attention of officers engaged upon works involving blasting.

The writing and the proof edition of his report to the Board covering in detail the ground of the various researches in connection with submarine mining has been continued by Lieutenant-Colonel Abbot; and the subjects of torpedo material, electrical operating apparatus, and torpedo insulated cable are completed to date, in addition to the three chapters made public in Professional Papers No. 23, Corps of Engineers, which was published last winter. The chapter on fish torpedoes is now in hand and well advanced.

River and Harbor Improvements, &c.-The Board during the year has also prepared and forwarded reports upon the following projects referred to it:

1881. July 25. Upon project of Major Mansfield for improving the harbor of Brazos Santiago, Texas.

August 6. Supplementary report upon project of Colonel Macomb for improving Christiana River, Delaware.

December 6. Upon question of improvement of Beaufort Harbor, North Carolina, and project of Captain Mercur for application of appropriation for same object.

1882. March 11. Upon project of Captain Heuer for improvement of Sabine Pass, Texas.

March 14. Upon plan of Major Barlow for improving the navigation of the Thames River from Norwich to Easter's Point, Connecticut.

In addition to their duties with this Board, the several members have been engaged upon special Boards and various duties, viz:

General Tower has served during a great part of the year upon the Board authorized by Congress to examine inventions of heavy ordnance and improvements of heavy ordnance and projectiles. By direction of the Secretary of War he also made an examination, during the summer of 1881, of various works on the New England coast.

General Newton has been engaged upon the important works of river and harbor improvement under his charge, and has also served during most of the year as a member of the Warren Court of Inquiry.

General Abbot has continued in command of the Engineer School of Application at Willet's Point, Long Island, and has served on special Board for examination of candidates for promotion in the Corps of Engineers.

BOARD OF ENGINEERS FOR THE PACIFIC COAST.

This Board has consisted of the following officers of the Corps: Lieut Col. C. S. Stewart; Lieut. Col. R. S. Williamson, until retired, June 23, 1882; Lieut. Col. G. H. Mendell; and Capt. A. H. Payson, recorder.

No special subjects have, during the past fiscal year, been referred to this Board for consideration and report.

BATTALION OF ENGINEERS AND SCHOOL OF APPLICATION.

The strength of the Battalion of Engineers on June 30, 1882, was 14 commissioned officers and 193 enlisted men. The legal organization authorized 752 enlisted men, but at present only 200 are allowed to be recruited.

The Battalion is commanded by Lieut. Col. Henry L. Abbot, and is stationed as follows: The field, staff, and band, and companies A, B, and C, at Willets Point, New York Harbor; Company D exists only on paper; Company E, at West Point, N. Y.

During the past year recruiting has been limited to re-enlistments and to men applying at Willets Point, and to occasional assignments of selected men from the General Depot at David's Island. The recruiting for Company E has been removed from the charge of Engineer officers and devolved upon the adjutant of the Military Academy.

The changes in personnel during the year have consisted of 2 deaths, 51 discharges, 8 desertions, 34 re-enlistments, 7 enlistments, 11 recruits joined from depot, 2 deserters apprehended, and 1 transfer from other arms of service.

As heretofore, the troops have guarded the post and depot at Willets Point, where public property exceeding $3,000,000 in value is entrusted to their care. They have also performed much skilled labor, such as printing and photolithographing confidential documents pertaining to the torpedo service, executing the practical trials needful for developing our defensive torpedo system, instructing cadets at the Military Academy in sapping, mining, pontoniering, and military signaling, &c.

The great reason, however, why these troops are a necessity, and why their authorized strength should be largely increased, is to afford a nucleus of well-disciplined soldiers thoroughly instructed in the military duties of their special arm of service always ready for war with a civilized enemy. These duties are of the most important character, involving military reconnaissance, the duplication of maps in the field by photography and photolithography, the defense of our coasts by torpedoes, the attack and defense of fortified positions, the building of military bridges, the construction of land-mines, &c. Rapid progress is making in all these branches of the art of war, and we cannot afford as a nation to neglect them.

The School of Application for officers has made steady progress dur ing the past year. It includes not only the strictly military branches of the engineering profession, but many civil branches as well, such as practical astronomy, meteorology, and barometric hypsometry, surveys, tidal and current measurements, electricity in its practical applications, and other similar work involving familiarity with the use and the handling of delicate instruments and with refined modern methods. This school is the only place in this country where close and systematic study is given to the various problems involved in submarine mining for coast and harbor defense. A class of two artillery officers has been permitted to take this course during the past season with a view to qualifying for detail in this branch of the Engineering Service; and all the young officers assigned to the Corps of Engineers are now required to make themselves thoroughly familiar with the subject before going to other duty.

The enlisted men of Engineers receive theoretical as well as practical instruction at Willets Point, and I desire to again urge the importance of increasing their numbers sufficiently to meet the military need of the country for a larger number of soldiers trained in their responsible

duties. The cost will be trifling in comparison with the interests at stake.

(See Appendix No. 4.)

ENGINEER POST AND DEPOT OF WILLETS POINT, NEW YORK HARBOR.

This post is the School of Application for the Engineer branch of the service, where officers newly assigned to the Corps of Engineers complete the purely theoretical course of instruction received at Willets Point, and where the enlisted men of the Battalion are trained in submarine mining, pontoniering, sapping and mining, military-map-making, and other duties pertaining to this arm of the service.

The depot contains the more delicate parts of the submarine mining material purchased for the defense of the coast; the bridge equipage of the Army; the Engineer trains for field service; the astronomical, geodetic, and surveying instruments in store for the general use of the Corps of Engineers. The enlisted men of the Battalion guard and care for all this property.

The usual appropriation of $4,000 for the current expenses of the depot, including repair of instruments, and of $1,000 for the purchase of materials for the instruction of the troops in their special duties is requested. Also the sum of $3,000 for continuing the construction of the needful public buildings which are now nearly completed.

These works are in charge of Col. John Newton, Corps of Engineers.

Statement of mastic and bitumen stored with post quartermaster at Governor's Island, New
York Harbor.
Mastic:

The funds with which the works for the improvement of rivers and harbors were prosecuted during the past fiscal year were derived from the appropriations of the act of March 3, 1881, together with such balances as were on hand from previous appropriations.

A brief statement is given below, setting forth the condition of each improvement, the extent of the work performed during the year, the amount of money expended, and an estimate of the probable cost of com