These are, of course, only some of the items. The total production authorized was valued at approximately $45,000,000.

The remarkable development and improvement of military radio equipment which has taken place under the direction of the Signal Corps during the last 18 months will undoubtedly materially change the system of Army communications and even the tactical use of military equipment and personnel. A typical example of this development is the airplane radio telephone, described elsewhere, the use of which has made possible the "voice-commanded air squadron." The military value of an air squadron has been enormously increased by virtue of this device, which enables the squadron commander to direct the movements of the individual airplanes in any manner which circumstances may require.

Certain other radio devices recently perfected, the nature of which can not be revealed, will undoubtedly affect the tactical use of troops to such an extent as to make certain kinds of radio equipment as indispensable to the operations of military units as the rifle or the machine gun.

LINE EQUIPMENT.

The first requisition for line equipment for France called for the construction of 500 miles of telephone and telegraph main pole lines, carrying 10 copper telephone and telegraph wires. It was found that ship space could not be spared for poles in such quantity. Consequently a forestry unit was sent to France to get these poles from the French woodlands. All of the other materials for the 500 miles of line, together with materials for approximately 600 miles of extensions, were procured in the United States and shipped to France within six months after the requisition was received. This material was secured in such short time only by the cooperation of the large commercial companies in the United States, who literally stripped their warehouses bare of their supplies.

In the late summer of 1918 the American Government began anticipating the advance of the allied forces into Germany, and the Signal Corps put into production a reserve equipment for long distance line approximating 500 miles. Soon there was received from France a cablegram asking for the shipment of this material, and it was all floated before the armistice. However, as it turned out, this equipment was never required, since the terms of the armistice gave the American forces the German telephone and telegraph lines in the occupied territory.

This line equipment was all of a type standard in the United States. For the fighting zone special line equipment was required. Before the war with Germany American signal troops had set up their emergency telephone and telegraph lines on the standard "lance poles." These poles served admirably in open warfare, but proved to be impracticable for the static conditions of fighting in France. After a considerable supply of lance poles had been shipped abroad their production was curtailed. Thereafter the trench telephone and telegraph lines were supported on short stakes with special cross arms, in appearance the conventional telegraph poles in miniature. The enormous mileage of trench lines called for a great quantity of insulators and cross arms. The wastage of these fittings, due to their being exposed to artillery fire, became increasingly greater in the closing months of the war.

In wire itself, the American production was enormous. This production included the commercial type of copper line wire and the drop wire for connecting up individual telephones to the pole lines. Much commercial cable for connecting congested centers with branch switchboards was also required. Yet all of this wire used in the system within the Service of Supply was but a small quantity compared with the requirements in the fighting zone.

The production of double-conductor wire, or the so-called outpost wire of No Man's Land, which had relegated to the scrap heap the standard field wire of open warfare, necessitated an extraordinary effort. The wire had to be light enough for easy transportation and laying, strong enough to withstand the abrasions from traffic crossing it as it lay on the ground, and exceedingly well insulated. The first estimate was that an American Army in the field might use 1,000 miles per month of outpost wire. When the first American force actually went into action, in the spring of 1918, a reserve supply of 20,000 miles of outpost wire was in the American warehouses in France, with a vast quantity of cable in reserve. Cable, at first used in large quantities at the front, was invariably buried several feet underground and abandoned at every change of headquarters.

As the fighting grew more intense and covered a wider and wider area, the wastage of outpost wire became enormous. The demand of our forces for cable dropped to a negligible quantity, but wire requirements rose. Outpost wire became the main dependence of ourselves and the allies for all communication in the active sectors. A higher quality of wire was specified. So great was the destruction of wire that by July, 1918, the original estimate of 1,000 miles per month to be supplied by American factories had jumped to 20,000 miles.

As a substitute for outpost wire to fill the immediate needs the familiar twisted drop wire, with which the ordinary telephone is connected with the main circuit, was adopted. Our field officers liked drop wire, its only objectionable feature being its relative bulk. All available drop wire in the United States was shipped across, and its manufacture was pushed until the new type of outpost wire could be produced.

The Signal Corps supplied the mounting needs of the American Expeditionary Forces through August and September, 1918, with the available drop wire plus the growing production of the new outpost wire. In early August all the wire makers in America were summoned to a conference, in which the Signal Corps made known the necessity of pushing production. The result was an expansion which reached a total production of 40,000 miles of outpost wire in November.

Just before the armistice was signed, the American Expeditionary Forces indicated that they would require 50,000 miles of outpost wire every month, beginning in January, 1919. This requirement had already been fully anticipated, since the American manufacturers had set for themselves a maximum production of 68,000 miles per month by August, 1919.

To secure this production every wire mill in the United States worked 24 hours per day. When the production was at its height, inquiries came from the allied governments, indicating that they would call on American wire makers for a quantity of wire equal to what the latter were already producing for the American Expeditionary Forces. In other words, this proposition called for the doubling of a production which had already attained great size. Yet, had the fighting continued, there is every reason to believe that the industry would have risen to the demand.

The production of outpost wire was an intricate operation. To fill the demand for 50,000 miles of outpost wire a month called for 300,000 miles of steel strand and 400,000 miles of bronze strand every month. The steel strand had to be given repeated heat treatments before it had acquired the necessary tensile strength.

ELECTRIC BATTERIES.

The American Expeditionary Forces consumed great quantities of electric batteries, the familiar dry battery of commerce being most used. Toward the end of the fighting arrangements were being made to establish in France a plant at which dry batteries would be assembled by French labor, utilizing parts made in America. The necessary apparatus and materials for the first operation had reached France prior to the armistice, but the plant was not in production at that time.

Storage-battery requirements of the American Expeditionary Forces were heavy and exacting. The storage battery was the only practicable source of electrical energy for the operation of small portable radio outfits. Field conditions required a storage battery that would not spill its contents, with a jar not easily broken, the whole equipment being as light as possible. A rubber composition jar was finally adopted.

The chief reliance of the American Expeditionary Forces was in storage batteries of European manufacture, which were to be used until American production got underway. When by the summer of 1918 America had perfected her own designs of radio equipment, the Signal Corps took up the matter of storage batteries for radio and decided upon types. This was in July, 1918. A conference of battery manufacturers was called and the orders were allocated among practically all the storage-battery plants in the United States that were in a position to undertake quantity production. The end of hostilities stopped this production on the eve of heavy deliveries.

FIELD GLASSES.

When the war began, the Signal Corps had the duty of providing field glasses for all branches of the Army, issuing them to noncommissioned officers and selling them at cost to commissioned officers engaged in combat. The first estimates showed that these glasses would be needed by the tens of thousands, whereas the manufacturing facilities in the United States had turned them out merely by the hundreds.

The optical-glass industry had never been developed in America, our field glasses being supplied with lenses of European glass, and principally German glass. In 1914 the imports of optical glass were $641,000 in value. The following year they were almost nothing. The advance of the German army toward Paris encompassed the glass plants of Belgium and many of those of France. England needed the entire output of her own glass factories.

In the autumn of 1914 the American optical-instrument makers began to develop an optical-glass industry, largely stimulated by the possibility of obtaining heavy orders at high prices from the British, French, and Russian governments. The most important work was done by the Bausch & Lomb Optical Co., of Rochester, N. Y.; the Spencer Lens Co., of Buffalo, and the Pittsburgh Plate Glass Co., of Pittsburgh. They were aided by the United States Bureau of Standards and by the geophysical laboratory of the Carnegie Institution. The Bureau of Standards established a laboratory at Pittsburgh where experiments were conducted with 30-pound pots of glass.

Optical glass differs greatly from ordinary glass. It must be clear, without striae, and there must be no strains in it, resulting from the final stirring and cooling. It must give a high transmission of light.

About the time of America's declaration of war the American experiments had produced glass suitable for optical instruments. This glass, however, was being turned out in quantities quite insufficient to meet the demand during the first few months.

In addition to the difficulties surrounding the glass supply, there was only a limited number of establishments capable of manufacturing field glasses after the glass was procured. These concerns were located principally in Rochester, N. Y., where they had been manufacturing a wide variety of optical instruments, including opera glasses, camera lenses, scientific and educational apparatus, battery commanders' telescopes, marine glasses, microscopes, and gun sights. In order to meet the war requirements of America for field glasses, these factories had to install large quantities of new equipment and to run day and night. The equipment consisted of lens-grinding apparatus, lathes, dies, and automatic screw machinery.

In addition to the Rochester factories there was a concern in Denver, Colo., the Weiss Electrical Instruments Co., which in a smaller way had been manufacturing surveyors' levels and other engineering apparatus. The Talbot Reel & Manufacturing Co., of Kansas City, had been making fishing reels in a small plant about 30 feet square. This factory was purchased in 1917 by Mr. L. Harris, who, after finishing a contract for gun sights for the Ordnance Department, built a factory especially for the production of Army field glasses and reached the quantity manufacture of these instruments before the armistice came. The chief center of supply, however, continued to be Rochester, where the plants of Bausch & Lomb, the Gundlach-Manhattan Optical Co., and the Crown Optical Co. are located. These factories expanded many times, and the output of field glasses went beyond what the executives at the outset of the enterprise imagined could be possible.

The Bausch & Lomb Co. was started in Rochester about 50 years ago by J. J. Bausch, who was born in Germany. The plant developed gradually, making a full line of spectacle lenses and optical instruments. The Carl Zeiss Works, of Jena, Germany, had a financial interest in the plant, and Bausch & Lomb had a financial interest in the Zeiss plant. This connection, however, was dissolved in 1915, when Bausch & Lomb took on contracts for the manufacture of field glasses for the British, French, and Russian governments.

Before 1914 this concern had never manufactured more than 1,800 pairs of field glasses in a year. The output was speeded up until in November, 1918, a total of 3,500 pairs was being produced each week, while the development was aiming toward an output of 5,500 pairs of glasses per week beginning in January, 1919. At the date of the armistice the Bausch & Lomb factory had a floor space of 32 acres and employed 6,000 men and women.

The Gundlach-Manhattan Co., which had made camera lenses chiefly, was eventually able to produce 600 pairs of field glasses a week. The Crown Optical Co. was not so rapid in its expansion; and in late 1917 the Navy Department commandeered it and thereafter operated it in charge of Lieut. Commander L. C. Scheibla. Under naval management the output of this factory increased so that the Signal Corps was able to obtain from it about 1,200 pairs of high quality field glasses each week, the plant continuing also to supply the needs of the Navy.

Out of a situation that seemed impossible at the outset the Signal Corps built up an industry within a comparatively few months which provided all the field glasses that were necessary in the operations of the American Expeditionary Forces. Often to keep the optical factories equipped with sufficient workmen the Signal Corps obtained the furlough of drafted men with experience in this line so that they might go to work making field glasses.

All Army organizations except Artillery were supplied with a six-power glass having an angular field that took in a view 150 yards wide at a distance of 1,000 yards. The glasses were of the prismatic type with individual focus for each eye. Each glass was provided with a leather carrying case and shoulder strap. On the top of the case a compass was mounted.

The Artillery organizations were supplied with eight-power field glasses, all of which were purchased in France.

The total requirements of the American Expeditionary Forces for field glasses of the six-power type during the period of hostilities were approximately 100,000 pairs. The total shipments from America were approximately 106,000 pairs.

MISCELLANEOUS SUPPLIES.

The Signal Corps took up with three concerns—the Hampden Watch Co., the Illinois Watch Co., and the Elgin Watch Co.—the matter of providing wrist watches for the Army. A 7-jewel movement was adopted as standard for issue to troops and a 15-jewel movement for sale to officers. A waterproof case was adopted, bearing the serial number of the movement on the outside, the case being so constructed as to require a special tool to gain access to the movement.

The production of wire carts for the Signal Corps did not exceed 25 per year prior to 1917. The demand for these carts, which were hard to build, increased at such a rate that during the autumn of 1918 the matter of procuring them was one of the most serious production problems faced by the Signal Corps.

The Holmes Automobile Co., of Canton, Ohio, abandoned the production of automobiles and in September, 1918, turned over its entire plant to the production of wire carts. Other manufacturers were the George B. Marx Co., of Brooklyn; the J. G. Brill Co., of Philadelphia; the American Instrument & Tool Co., of New York; and the Wesel Manufacturing Co., of Brooklyn. In all, 721 wire carts were manufactured and 327 shipped overseas.

A total of 2,402 tool chests for the Signal Corps was produced during the war period. The plan eventually adopted was to split up the orders for tools among the various manufacturers and to give the manufacture of the empty chests to prison labor at Fort Leavenworth, where the tools were to be shipped and packed in the chests. This plan, however, required the construction of a special building at Fort Leavenworth, and in the meantime the assembling of tool chests was conducted at the Signal Corps supply depot at Philadelphia and at the port of embarkation. The armistice stopped the construction of the assembling factory at Fort Leavenworth.

The Signal Corps produced a suitable number of gas alarm signals known as strombos horns. This equipment consisted of an alarm horn operated by air pressure acting against a diaphragm and thereby producing a loud and distinct chatter. Compressed air was supplied in small steel cylinders connected to each horn by hose. The air tanks were charged behind the lines from a portable air compressor which could pump into several cylinders at once. The horns were manufactured by the Klaxon Co., of Newark, N. J., the cylinders by the Harrisburg Pipe & Pipe Bending Co., Harrisburg, Pa., and the air compressors by the Ingersoll-Rand Co., of New York.

Flag kits were not used to any great extent by the American Expeditionary Forces, although large quantities of these were produced in this country.

The Signal Corps originally had jurisdiction over all war photography, either of land or air, except for a small amount conducted by the engineers in connection with their own operations; but later aerial photography became a branch of the Military Aeronautics and Aircraft Bureaus. After that the Signal Corps was charged with taking all photographs of historical nature or other interest.

In connection with this work two types of cameras were necessary—still cameras and motion-picture cameras. Later in the war there was being developed a new motion-picture camera which was expected to be the ideal type for use in the field.

It was with great difficulty that a sufficient number of photographic lenses was obtained for the use of military cameras, since the large lens factories of America were tied up with other war orders. A campaign was conducted by the leading newspapers and magazines of the country which resulted in the Government's securing from amateur photographers a large number of high-grade lenses, mostly of foreign manufacture.

The Signal Corps scattered its camera operators broadcast over the country, photographing cantonments and other war activities to the most minute details. These photographs and films were then made public in newspapers, periodicals, and motion-picture theaters throughout the United States, with the result that the people saw with their own eyes how their soldiers were preparing themselves for the defense of the Nation.

An interesting development of war photography was the production of motion pictures showing the training of soldiers. Many pictures were taken to show graphically on the screen the different chapters of the Army drill regulations. These pictures will have a future use to the Government in training soldiers efficiently in the shortest possible time.

The Signal Corps photographers also developed a new kind of history of the war, a history written entirely in pictures for future generations to scan.

PIGEONS.

Although nearly every European army for 40 years has trained the carrier pigeon to be a field messenger, the American Army never adopted the bird until 1917. In a single year the Signal Corps established hundreds of pigeon lofts in this country and overseas and bought and trained more than 15,000 pigeons for service in France. In actual use on the field the pigeons delivered more than 95 per cent of the messages intrusted to them, flying safely through the heaviest shell and gas barrages.

The standard pigeon loft adopted by the Signal Corps had a unique trap arrangement which permitted the entry but not the exit of returning pigeons, and an electrical alarm which automatically notified the attendants of an arrival. Such lofts, however, were of the stationary type and not practicable for use in France. For the American Expeditionary Forces the Signal Corps purchased mobile lofts. It was found that pigeons would come home as well to mobile lofts, which were constantly changing position, as they would to stationary lofts. The first mobile lofts built in the United States were top-heavy, but this defect was overcome by increasing their width and adding heavier wheels. They were all built by the Trailmobile Co., of Cincinnati, Ohio.

Civilian pigeon fanciers were appealed to and urged to breed young birds to stock the Government lofts. The Signal Corps distributed small aluminum bands to be put on the legs of squeakers, as the newly-hatched pigeons are called, which were intended for sale to the Government. The uniform price of $2 per bird was paid, and over 10,000 youngsters were bought for stocking purposes.

Tons of pigeon feed were purchased and shipped to Europe. Some of this grain, such as millet, Argentine corn, pop corn, hemp seed, and Canada peas, was hard to obtain; but nevertheless the supply was well maintained. It was shipped in hermetically sealed containers to prevent it from becoming mildewed.

The American Army copied the French and English models of willow and reed baskets to hold the birds. One type of basket was carried on the back of the soldier and contained small corselets in which the pigeons were securely fastened. Corselets were suspended from the sides of the basket by elastic contrivances permitting considerable joggling without injury to the birds. All of these baskets were made by the A. L. Randell Co., of Chicago.

Message books were manufactured in accordance with a French model. After the message had been written, it was placed in an aluminum capsule which was fitted in a holder of aluminum. This holder was attached to the pigeon's leg by means of aluminum bands. These bands were found to break easily, and pure copper bands were later substituted. The message holders were manufactured by Thomas A. Gey, of Norristown, Pa.

Thousands of items of supply were included in the supply schedules of the Signal Corps. In the following lists some of the more important items are shown, the production indicated in each case being that between April 6, 1917, and November 11, 1918.