52 THE AMERICAN MONTHLY [Mar 
times with a corner of the wax, gently heated over a lamp, 
and then spread with the point of the fore-finger. Due 
care is taken to see that the small picture is in the centre 
of the focussing screen, and that no adjustment of colli- 
mation is necessary. 
The negatives to be copied were quarter-plates illumi- 
nated by a 4in. condenser placed immediately behind them, 
and in almost close contact with them, their distance from 
the camera being regulated,by the size of the micro-pho- 
tograph desired with each object-glass used. It was found 
that with artificial light no other method of illumination 
would suffice to give an evenly lighted copy. The object- 
ives used were Zeiss 75mm. and 35 mm. apochromatics. 
The lamp used was an ordinary paraffin lamp with a fin. 
wick placed in the focus of the condenser, and with such 
a light it was found that with Ilford ordinary plates, and 
the negative nearly 3ft. away, using these objectives, an 
almost instantaneous exposure sufficed. Everything being 
ready, the picture is roughly focussed by the movement 
of the camera itself, while the fine focussing is done by 
the rotation of the tube in the jacket by means of the fine 
screw. <A focussing glass having considerable magnify- 
ing power is necessary, owing to the smallness of the pic- 
ture. The camera may, of course, be so made as to take 
any size of plate, but it was found that those used were 
perhaps the most convenient of all, and although not 
transparency plates, good results were obtained. It will 
be seen from the above that no focussing screen on a sep- 
arate frame was used, the focussing glass being carried 
in the dark slide itself, and removed each time the sens- 
itive plate was put in, thus preserving the perfect regis- 
ter obtained. Probably those who make it their business 
to do this kind of work may have very perfect and expen- 
sive and rigid forms of apparatus; but the above acces- 
sory, when used with a somewhat rigid form of camera, 
does give good results.—Hnglish Mechanic. 
