grouping the machines in such a way that the daily output can be increased or decreased by running one or more groups.

123. The new gas heating plant for forging, annealing, etc., has been completed and has worked satisfactorily.

124. There have also been set up at the water shops 16 new furnaces in the forge shop and 6 new annealing furnaces.

125. A recent appropriation of $5,500 will enable us to put in a new penstock and wheel, to run two 100-kilowatt generators-one for each floor-for power and lighting.

126. A new electric-light plant of sufficient capacity to light all the shops has been installed. The old system that formerly lighted a portion of the shops has been altered and utilized for general lighting of quarters, barracks, stables, and of the grounds of the post.

127. Magazine rifle and carbine.-In addition to the manufacture of the service rifle and carbine of latest model, and spare parts for them for issue, satisfactory progress has been made with the drawings and fixtures for the new rifle. The order for 5,000 will, it is hoped, be completed early in the coming spring. As the new magazine rifle is chambered differently from the present service rifle, corresponding changes will have to be made in any machine or automatic guns hereafter to be procured. The automatic machine gun at present in use has been fairly satisfactory, but the Department will take advantage of the change in ammunition above referred to to make the necessary experiments to obtain the most reliable automatic machine gun in the market.

128. Authority having been granted, 100 rifles having barrels shortened 4 inches were made and have been issued to get an expression of opinion from the infantry as to the desirability of thus reducing the weight of the rifle. If it should not be too heavy for the cavalry, the manufacture and issue of but one arm for both services might be an advantage. With the issue of this short rifle it is thought that in each company there should be selected sharpshooters to be armed with a longer rifle provided with telescopic sight.

129. Arms manufactured during the year.-Twenty thousand magazine carbines, caliber .30, model 1899; 43,246 magazine rifles, caliber .30, model 1898, and 1,056 swords and sabers have been manufactured. A large number of appendages and spare parts have been manufactured and also many arms have been altered and repaired.

130. Subcaliber attachments for 3.2-inch guns, 7-inch howitzers, and 5-inch siege guns have been manufactured.

131. Thirteen thousand nine hundred and fifty-six Colt revolvers of various calibers have been inspected and accepted; also a number of automatic guns, with their carriages and mounts.

132. Experimental firing.—In this Department firings have been made for a variety of purposes, the most important being for testing

various rifles and automatic pistols submitted by inventors, sighting of experimental short (26-inch) barrel recently issued, making comparative tests of riflings differing as to twists and number of grooves, determination of a suitable cartridge for gallery practice, and also for the new 2,300 feet per second magazine rifle. These firings have involved determination of accuracy, muzzle velocity, pressure per square inch, and many other incidental tests.

WATERTOWN ARSENAL.

133. The shops of this arsenal have during the year been employed to their full capacity in the manufacture of gun and mortar carriages, shot trucks, projectiles, implements, targets, and parts for the repair, alteration, and improvement of the armament of the seacoast fortifications of the country. It is the central supply station upon which requisition is made directly by district armament officers for such spare or new parts and for such alteration and repair work as can not be conveniently or economically obtained in the vicinity of the fortification concerned.

In addition to these operations pertaining to the country at large this arsenal is specially charged with the repair, alteration, and improvement of the armament in the northern district (i. e., the New England coast, down to and including New London, Conn.), which duties have been satisfactorily performed and have resulted in a high state of efficiency of that armament.

134. The following gun and mortar carriages have been completed during the year:

12-inch disappearing carriages, L. F. model 1897.

12-inch barbette carriages, model 1892

12-inch mortar carriages, model 1896.

10-inch mortar carriages, model 1900..

8-inch disappearing carriages, model 1896.

1

1

6

1

3

1

5-inch barbette proof carriage for Sandy Hook. 7-inch mortar carriages, with platforms...

22

135. The Secretary of War having approved the manufacture of a disappearing carriage for the 16-inch rifle, instructions were given to have the drawings prepared and the manufacture undertaken at this arsenal. The engineering construction of this carriage is in charge of Gen. A. R. Buffington, retired, who approves all drawings before work in accordance with them is executed. Work on the carriage is reported to have progressed satisfactorily.

136. The capacity of the shops has been slightly increased during the year by the installation of a few machines, and greater economy of manufacture has been attained by changing the method of transmitting power from the main machine shop to the extension shop and foundry from wire rope to electricity.

137. The iron castings of the foundry have further improved in character, and the forging of certain bronze castings having proved conclusively of great advantage the practice has been continued.

138. The manufacture of cast-iron projectiles in limited numbers continues to be satisfactory, and the loss always attending the use of the fine grade of iron, especially in smaller castings, shows gratifying decrease. The projectiles for the 16-inch breech-loading rifle are brought to a uniform weight of 2,400 pounds each, the mean variation in weight being 9 ounces, and upon cutting them open they show soundness to the center.

139. The output of the machine shops as to quantity and quality has been satisfactory. The considerable number of men necessary for detached work at the fortifications is, at times, a source of embarrassment, as the class of men necessary for this work is not always readily obtained, and especially for short periods and short terms of employment.

140. The forging shop turns out good work, and there is such an economy in the use of broken armor plate that all fragments of 2 square feet and of thickness above 4 inches which can be sent from the proving ground can be readily utilized.

141. A better system of fire protection is now being installed, thus meeting a necessity which has existed for some time. The new system contemplates the introduction into the shops and detached buildings of a system of standpipes with the necessary hose for each floor, which, in case of fire, can be brought into action before a steam fire engine arrives.

142. Congress has, by appropriating the necessary funds, authorized the construction of new barracks, and the necessary work will be undertaken and completed as early as practicable.

143. The operations of the testing department during the past year are given in detail in the usual report "Test of metals, etc."--published annually. Many of the investigations made during the past year are of special importance to ordnance and mechanical engineers, and undoubtedly the detailed report of the results of these investigations will be of much interest to manufacturers and designers, civil and military.

144. An investigation into the strength of "streaked" and unstreaked gun forgings was made by means of hydrostatic pressure applied to two hoops for 10-inch rifles prepared by the Bethlehem Steel Company and tested in the presence of a representative of that company. The hoops were turned down to a thickness of wall of 0.50 inch each. One hoop contained numerous short, dark, interrupted lines or seams where the metal appeared to lack continuity, a condition which has received the designation of "streaked metal." The other hoop was free from these lines, and furnished an example of a sound forging so

far as could be visibly ascertained. The hoops were tested to destruction by interior pressure.

145. The unstreaked hoop displayed a tensile strength and elongation in excess of the ordinary tensile specimens representing the physical properties of the same steel, while the streaked hoop showed a deficiency in corresponding properties.

146. The elastic limits under hydrostatic tests coincide with the specimen tests of the material. Each hoop successfully endured a stress just below its elastic limit, repeated five hundred times in each case, without apparent injury. The appearance of the streaks or seams in the metal acquired greater prominence as the test advanced beyond the elastic limit, and eventually the streaked hoop fractured longitudinally, beginning at the principal streak. 147. The main results of the tests were as follows:

148. The examination of the internal strains in a specially treated tube, heated and quenched at the bore, has been made, and the presence and magnitude ascertained of longitudinal compressive strains in conjunction with tangential compression at the bore.

149. The objects of the test were to ascertain if the internal strains in a thin transverse section taken from a hollow gun forging represent the strains in the intact forging; that is, whether the state of the metal in a detached slice may be accepted as an index of the state of the metal in the forging, having reference to the tangential internal strains introduced by the method of heating and quenching a tube at the bore. Also to obtain data with reference to the magnitude of the accompanying longitudinal strains, and, furthermore, the effect of exposure to higher temperatures in the elimination of strains introduced by heat treatment.

150. The conclusions from the tests were:

(1) The detached slices represent the state of the metal in the intact tube with respect to the direction of the internal strains, and approximately with respect to their magnitude.

(2) The metal at the bore is under a higher degree of initial compression than indicated by the detached slices. In the present tests the difference is 3,000 pounds per square inch, mean compressive stresses in the slices.

(3) Longitudinal strains of compression at the bore are present, which may be taken approximately at three-fourths of the tangential strains. In the present instance the mean results show the longitudinal strains are 78 per cent of the tangential strains.

(4) The ends of the tubes are bell shaped in consequence of the longitudinal compressive strains at the bore.

(5) The state of the metal at the bore, at the ends of the tube, by reason of the bell-shaped form, is under greatly diminished tangential strains.

(6) Annealing eliminates internal strains. The strains which are introduced into the forging by reason of sudden quenching from a moderately high temperature are removed upon exposure to a moderately high temperature when slowly cooled.

(7) The elimination of internal strains was practically completed upon exposure to 1,100° F. About one-half the primitive strains. remained after exposure to 700° or 800° F.

(8) This relief of internal strains is accomplished without material relative movement of the parts of the forging. That is, the reacting parts which were under opposite kinds of strains, tensile and compressive, maintain their dimensions and relative positions after annealing, unchanged.

151. In the line of work on general engineering subjects, investigative tests on the properties of natural and Portland cements have been continued. There were tests on suspension rods from the Brooklyn Bridge, including the examination of some of the rods which were discovered fractured in the bridge in July, 1901, and other rods from the adjacent parts of the structure. The progressive character of the fractures was shown, and incipient cracks found in the adjacent rods.

152. The tests on repeated alternate stresses appear to have demonstrated that some grades of steel have a limit of practically indefinite endurance under fiber stresses in the vicinity of 40,000 pounds per square inch, although the stress is a close approach to the maximum, and a further advance of load soon ends in rupture.

FRANKFORD ARSENAL.

153. Artillery cartridge plant, carpenter shop, and storehouse.-For the reasons explained in the last annual report, the three buildings comprising the factory for artillery metallic ammunition, the new carpenter shop, and the storehouse for factory supplies, have been combined under one roof.

154. Power plant, box making and packing shop.-Congress during its last session made an appropriation of $58,000 for a power plant for this arsenal and for the removal thereto of engines and boilers on hand, also $28,000 for a box making and packing shop for the smallarms cartridge factory.