114- 
minutes OE PROCEEDINGS OF 
Among the many applications of photography to the different branches 
of science, since its first introduction, my attention has been called to one 
of a novel description—viz.: to take the picture of a gun in the act of 
firing. This may appear an easy matter with any of the instantaneous 
processes in constant use, but the difficulty of opening and shutting the 
camera at the precise instant of time, is an operation too nice to be done by 
hand, inasmuch that the gun, on the instant of discharge, is set in motion; 
and a picture taken under such circumstances would be anything but 
satisfactory. 
Having designed an appliance to an ordinary binocular camera, I have 
succeeded perfectly in taking pictures of a gun at the time of discharge— 
the flash, smoke, and projectile are seen at the muzzle of the gun, which 
is clear and well defined in all its details, showing that the recoil had not 
then commenced ; the tube by which the gun is fired is also seen making its 
escape from the vent in a state of ignition. 
To give the reader a general idea of the apparatus and its mode of action, 
it is necessary to say that a galvanic tube is employed, such as is used in 
proving ordnance.* As this tube performs an important part in the present 
arrangement, it may be briefly stated, that the same galvanic current which 
fuses a small platinum wire in it, and by which the gun is discharged, is 
also used, at the same time, to open and shut the camera by the employ¬ 
ment of electro magnets. 
The camera which has been used in the experiments is a double one, 
capable of taking two views, and, by the arrangement, at different instants 
of time; a revolving disc moved by a spiral spring is placed in front of the 
lenses; in one position of the disc the camera is opened, and in another it is 
closed. 
When the gun is ready for firing the disc is wound up, and kept in its 
place by means of a catch controlled by an electro-magnet (connected with 
the gun by wires from the galvanic battery); on the instant of communi¬ 
cation being made the electro-magnet removes the catch, the disc rotates 
and opens the camera, and in this state it remains until the gun is fired j 
the current is then broken, and instantly the camera closes. 
The arrangement for keeping the camera open until the gun fires is very 
important, as there is sometimes a pause between contact being made with 
the battery and the discharge of the gun, in consequence of the galvanic 
power varying, and sometimes the tubes are not equally sensitive; in either 
case it would lead to a failure; this movement is the most important, but 
most difficult in the arrangement. 
It will readily appear that the same current being used to fire the gun 
and to open and close the camera, ensures such simultaniety of action as is 
unattainable by any of the ordinary means hitherto employed. 
By a slight modification of the apparatus, the flight of projectiles may be 
taken at any given part, of the range; also the appearance of iron plates, or 
the targets, at the instant of impact of shot or shell. 
P. MTQNLAY, 
Proof-Master. 
* Vide Vol. I. p. 362. 
