424 transactions of the american institute. 



Photosculpture. 



This invention of Mr. Willeme, a celebrated French sculator, was 

 explained at the recent meeting of the British, association for the advance- 

 ment of science, and a bust of the president, Sir Charles Lyell, n)ade by 

 the process, was exhibited. Photography furnishes a pattern by placing- -the 

 sitter in the centre of 24 cameras, when 24 profiles are taken at once. The 

 outlines thus secured are copied in clay in regular succession; the model 

 being turned one-twenty-fourth part of a circle for each profile. The 

 artist, having thus secured proportions true to nature, has still verge and 

 scope enough for h s genius in giving to the model the proper expression 

 and finish. The saving of time, both to the sitter and the artist, is the chief 

 advantage of this process. 



Electro-Ballistic Apparatus. 



This apparatus, invented by Major Navez, of the Belgium Artillery, is now 

 in use in England for determining the velocity of a projectile, or the rate at 

 which a shot proceeds from the muzzle of a gun. The novelty of Major Navez 

 consists in measuring, by means of electricity, the minute portion of the arc 

 described by a pendulum during the passage of the projectile through a 

 given space. 



Directly in front of the gun to be fired, and ninety feet from it, is placed a 

 screen, and in the same range, one hundred and fifty feet distant, is placed 

 another screen, the two being sixty feet apart. In each of these screens are 

 placed two wires, connected with a voltaic battery, so arranged that when the 

 gun is discharged the wires will be cut and the electric current broken. The 

 wires extend three or four hundred yards to the place where the measurement 

 is to be made. The wires from the screen nearest to the gun make an electro- 

 magnet of wrought iron, which attracts a piece of soft iron on the pendulum, 

 and holds it at the extremity of its arc of oscillation. To this pendulum is 

 connected another pendulum, or needle of soft iron, and, when free, swinging 

 over a finely graduated are, which is also of iron, and capable of being changed 

 to a magnet. The wires of the second or most distant screen are connected 

 with what the inventor calls "a conjunctor," and holds a weight which falls 

 the instant the current is broken, and, by means of a cup of mercury, imme- 

 diately completes another electric current which magnetizes the graduated arc. 

 When the gun is fired the projectile cuts the fii'st wire, and the pendulum pro- 

 per drops, carrying with it the index pendulum or needle. The projectile cuts 

 the second wire, and the arc becomes a magnet and instantly clamps the index 

 needle to the scale. The operator then reads from the scale the distance 

 traversed by the needle. A table has been prepared showing the time required 

 for the pendulum to move through any distance to one hundred and fifty 

 degrees. The time thus ascertained is divided into the distance between the 

 two screens, and the result is the velocity of the projectile. By means of this 

 ingenious contrivance a skillful operator is able to measure pretty accurately 

 one three-thousandth part of a second. 



