Velocities of Small Arm Bullets for First 100 Feet in Range.

So far as known to the writer, no chronograph in general use has yet proved equal to the task of measuring velocities over the short ranges of 5, 10 and 20 feet, and with sufficient accuracy to determine the rate of change in velocity of bullet.

When this was attempted with Boulengé instruments, for ranges as great as 50 feet, the data were full of contradictions.

In examining photo-velocimeter records on this point, what has been previously explained must be borne in mind, viz: (1) while bullet is passing over 20 feet of range the velocity of recoil is changing rapidly and errors in calculated velocities of bullet are liable to be relatively large. (2) The automatic iron target. seems to be slow in producing the secondary spark, and for this reason all velocities affected by the spark from this (No. 10) target are doubtful.

Small arm bullets should be considered as having their maximum velocities at points from 20 to 30 feet in advance of muzzle. They should gain in velocity over this distance, for the bullet is enveloped in gases moving in the same direction and with higher velocity than that of the bullet. The velocity of the light gases is soon reduced by atmospheric resistance, and the bullet on passing out of the gaseous envelope encounters a volume of air of abnormal density. This volume of air, on account of the forward motion imparted to it by powder gases, does not at once retard the bullet in proportion to its density; but when firing takes place in a closed gallery, with the last target near end of gallery, it is evident that the bullet must meet abnormal atmospheric resistance while moving over last one or two target intervals.

It is believed that the photo-chronograph referred to in introduction to this report will enable us to measure more accurately, than has heretofore been done, the change in velocity of projectiles due to atmospheric resistance. It will do this better than the apparatus used in this investigation because the recording. surface, instead of being attached to the piece, will be wrapped around a uniformly rotating cylinder.

Many exaggerated claims have been made for non-recoil propties in smokeless powders. They do give equal velocities to bullets, with less recoil, but the decrease in recoil is not the equivalent of reduction in weight of charge since the values of A are found to be higher than for the black powder.

Journal 3.

Experimental Investigations of First Stage of Recoil.

Under conclusion 6 of his report on "Development of a PhotoRetardograph, etc.," the writer suggested that satisfactory data on this stage of recoil could be obtained best by use of an instrument that would give a continuous and magnified curve of recoil as a function of time.

His experience in this investigation has confirmed him in this opinion. A comparison of curve No. 5, ptotted from the mean data of six observations, Plate II, with preceding curves, which were plotted from the data of a single observation, shows the apparatus used here to be equal, if not superior in accuracy, to the Sébert Velocimeter. Compare the relative grouping of plotted points about the mean curves, and bear in mind the fact that the times consumed by the small arm and the cannon in attaining maximum velocities of recoil were about 0.008 and 0.044 second respectively. The difficulty in obtaining experimental data increases very rapidly with reduction in time.

Three or four points, at most, of velocity curves during first stage can be approximately determined for cannon. For small arms neither the Sébert Velocimeter nor the apparatus used in this experiment is able to give any reliable data concerning acceleration of piece during development of maximum powder pressure.

THE SYNCHRONOGRAPH*.

A NEW METHOD OF RAPIDLY TRANSMITTING INTELLIGENCE BY THE ALTERNATING CURRENT. A REPORT TO THE BOARD OF ORDNANCE AND FORTIFI

CATION.

BY PROFESSOR A. C. CREHORE AND LIEUTENANT G. O. SQUIER.

In a general view of the technical history of the art of telegraphy, statistics show that at the present time, more than fifty years since the introduction of the telegraph, nine-tenths of the telegraph business of the world is transmitted by hand, in substantially the same manner as then. From an electrical point of view one naturally asks why it is, that during this period, which represents more electrical progress than all time previous, the rapid transmission of intelligence has not made more advance.

It is to experiments upon a new electrical system of rapid intelligence transmission and its possibilities, that your attention and consideration are invited. It is not intended to enter into a discussion here of the physical causes which have limited the speed and efficiency of the telegraph, but to acknowledge the great work of Wheatstone, Hughes, Edison, Delaney and others, who have brought rapid telegraphy to its present state of efficiency, and proceed to an explanation of the principles involved in the new system, and an account of the experiments already carried out in developing it. These experiments were conducted at the Electrical Laboratory of the United States Artillery School, Fort Monroe, Va., where the land telegraph and telephone lines were available for the actual trials described.

PRINCIPLES OF THE TRANSMITTER.

It is difficult to treat the subject of transmitters apart from their receivers, as any particular transmitter should be considered in connection with the limitations of its receiving instrument. If we could have a receiver sensitive enough to make a distinct and permanent record of every change in current transmitted over the line, provided the line were so situated as to be free from the disturbing influences induced by external causes, it would be ideal; and the discussion of transmitters would be simplified by reducing the elements to the line and transmitting A paper presented at the 115th meeting of the American Institute of Electrical Engineers, New York and Chicago, April 21, 1897.

Experimental Investigations of First Stage of Recoil.

Under conclusion 6 of his report on "Development of a PhotoRetardograph, etc.," the writer suggested that satisfactory data on this stage of recoil could be obtained best by use of an instrument that would give a continuous and magnified curve of recoil as a function of time.

His experience in this investigation has confirmed him in this opinion. A comparison of curve No. 5, ptotted from the mean data of six observations, Plate II, with preceding curves, which were plotted from the data of a single observation, shows the apparatus used here to be equal, if not superior in accuracy, to the Sébert Velocimeter. Compare the relative grouping of plotted points about the mean curves, and bear in mind the fact that the times consumed by the small arm and the cannon in attaining maximum velocities of recoil were about 0.008 and 0.044 second respectively. The difficulty in obtaining experimental data increases very rapidly with reduction in time.

Three or four points, at most, of velocity curves during first stage can be approximately determined for cannon. For small arms neither the Sébert Velocimeter nor the apparatus used in this experiment is able to give any reliable data concerning acceleration of piece during development of maximum powder pressure.

THE SYNCHRONOGRAPH*.

A NEW METHOD OF RAPIDLY TRANSMITTING INTELLIGENCE BY THE ALTERNATING CURRENT. A REPORT TO THE BOARD OF ORDNANCE AND FORTIFI

CATION.

BY PROFESSOR A. C. CREHORE AND LIEUTENANT G. O. SQUIER.

In a general view of the technical history of the art of telegraphy, statistics show that at the present time, more than fifty years since the introduction of the telegraph, nine-tenths of the telegraph business of the world is transmitted by hand, in substantially the same manner as then. From an electrical point of view one naturally asks why it is, that during this period, which represents more electrical progress than all time previous, the rapid transmission of intelligence has not made more advance.

It is to experiments upon a new electrical system of rapid intelligence transmission and its possibilities, that your attention and consideration are invited. It is not intended to enter into a discussion here of the physical causes which have limited the speed and efficiency of the telegraph, but to acknowledge the great work of Wheatstone, Hughes, Edison, Delaney and others, who have brought rapid telegraphy to its present state of efficiency, and proceed to an explanation of the principles involved in the new system, and an account of the experiments already carried out in developing it. These experiments were conducted at the Electrical Laboratory of the United States Artillery School, Fort Monroe, Va., where the land telegraph and telephone lines. were available for the actual trials described.

PRINCIPLES OF THE TRANSMITTER.

It is difficult to treat the subject of transmitters apart from their receivers, as any particular transmitter should be considered in connection with the limitations of its receiving instrument. If we could have a receiver sensitive enough to make a distinct and permanent record of every change in current transmitted over the line, provided the line were so situated as to be free from the disturbing influences induced by external causes, it would be ideal; and the discussion of transmitters would be simplified by reducing the elements to the line and transmitting A paper presented at the 115th meeting of the American Institute of Electrical Engineers, New York and Chicago, April 21, 1897.