SCIENTIFIC SUMMARY. 
109 
lamp and microscope, wliicli we should think must prove useful to the 
worker, and which is in principle the same as the table of Messrs. Loam and 
Fearns, which we some time since described and figured. It consists of a 
mahogany stand on three rollers, and provided with a lateral rod to which 
the lamp may be clamped. Its advantage in economising time will be ap- 
parent. Under ordinary circumstances, when the worker pushes aside his 
microscope, in order to continue some operation, he disadjusts the mirror 
for the lamp ; and when he next uses the instrument he must spend a few 
seconds in obtaining readjustment. By means of either Dr. Sedgwick’s or 
Messrs. Loam and Fearns’ tables he may push away his microscope, and on 
drawing it towards him again find the adjustment the same as before. 
Stereoscopic Binoculars. — Those who are at all interested in the principles 
on which the phenomena of binocular vision are at present considered to rest 
should read Dr. Carpenter’s paper on the “ Stereoscopic Binoculars ” in the 
last Quarterly Journal of Microscopical Science. We cannot see that the 
modification of Nachet’s stereoscopic binocular, which Dr. Carpenter 
describes, has any advantage over the ordinary binocular for the purposes 
of dissection ; but we doubt whether our readers can find elsewhere than in 
the article we refer to a really simple and comprehensive account of the 
optical advantages and disadvantages of the binocular microscope. 
Mr. Collins' Paraholic Reflector. — At the suggestion, we believe, of Mr. 
Bockett, Mr. Collins has constructed a parabolic refiector adaptable to his 
ordinary microscopic lamp, and which, from our examination, we feel much 
pleasure in recommending to our readers. The reflector itself is a silvered 
one of the usual parabolic form, but it is connected to a metal chimney 
which slides over the glass one, and has an aperture in the side opposite to 
the reflector. Thus not only may a very large and brilliant bundle of 
parallel rays be thrown directly on the mirror of the microscope, but all 
other rays being cut ofi*, the eye feels a relief in the surrounding shade, such 
as it does not obtain with any other contrivance. 
PHOTOGRAPHY. 
Action of Light on Chlo7'ide of Silver. — The Journal de Pharmacie re- 
cently published an interesting account of experiments performed by M. 
Morren, of the Academy of Marseilles, to demonstrate the true action of 
light on chloride of silver. M. Morren sealed up an equivalent of chloride 
of potassium in a small bulb, and in another placed a proportionate quantity 
of nitrate of silver. A perfectly clean glass tube, about a foot in length 
and an inch in diameter, being provided, the bulbs were dropped therein, and 
the latter two-thirds filled with solution of chlorine in water. The tube 
was then hermetically sealed, and on being smartly shaken the bulbs were 
broken, and their contents reacting on each other produced equivalents of 
chloride. of silver and nitrate of potash. When the tube thus prepared was 
exposed during many days to sunlight, it was found that the chloride of 
silver retained its whiteness until the water became decomposed by the 
chlorine acted upon by the light, and that it then assumed a red-brown 
