554 
POPULAR SCIENCE REVIEW. 
above the exact centre of a circular platform, hangs a plumb line, and 
around are four-and-twenty circular windows ranged at regular distances, 
which are four-and-twenty lenses pointing in a line, with four-and-twenty 
numerals painted at equal distances apart round the side of the smaller of 
the two circular platforms. When the subject to be operated on is placed 
on this platform so that the plumb-line indicates an imaginary line piercing 
the model’s head, and passing through the centre of the platform, four- 
and-twenty photographs are instantly taken by invisible operators (see cut), 
and so far as regards the sitter the process is complete. 
Not so, however, with regard to the result. In a dark room a magic 
lantern is placed opposite a large sheet of ground-glass. Beside this 
ground-glass stands a bench, and upon this bench a disc divided into four- 
and twenty spaces, each one numbered. Upon this disc is a roughly 
shaped-out mass of modelling clay, through which passes a rod of iron in 
the direction assumed by the imaginary line above noticed. The operators 
having taken their places, one attends to the lantern, and one so arranges 
a pantograph, that when its tracing-point touches the ground glass, a 
cutting-point at its other end touches the modelling clay. And now the 
work begins. The four-and-twenty photographs on glass previously taken 
have been fitted in numerical order around the edge of a disc, which turns 
like the wheel of a rudder, and is made to throw each of its four-and- 
twenty images slowly, and one after the other, on the sheet of ground- 
glass behind which stands the man with the pantograph. This operator 
carefully traces the outlines of each photograph with the fine tracing- 
point of his instrument, and as he does so, the cutting-point as slowly 
cuts away the modelling clay, until when he has traced the outlines of one 
photograph, there is its profile cut in the clay. The disc of the photo- 
graphs makes one turn, the disc on which the modelling clay stands does 
