230 EH. Emerson on Improvements in the Photographic Camera. 
i. on the same plate, the left hand view being taken by the 
portrait combination, and the right-hand view being taken with 
a quartz lens, or a common glass lens, or a pin-hole, as the case 
might be. The scenes or objects photographed were always 
sean to the full light of the sun; and the plate, in each pair 
of experiments, was, of course, subject to a uniform bag 0 
adr similar conditions as to collodion, baths, &c. 
able to compare the results of the various experiments side i 
side with the action of the achromatic combination; as follows— 
Portrait combination, 6 inches focus. Quartz lens, 6 inches ip 
1, One second exposure, $ inch dia- 
phragm. A pretty fair negative. 
2. Thirty seconds exposure, finch 2. Thir 
diaphragm, good negative, would 
stand a = magus power of 30 
diame not ~~ a eeruae power of 
5 diameters. 
Two ene exposure, py inch 
3. Two minutes exposure, to inch 3, 
diaphragm, no quicker action, no 
diaphragm, strong ne ya view 
sharp all over the field, would 
stand a magnifying power of 100 
diameters. 
4, Two and a half minutes exposure, 
inch diaphragm, negative 
esl but would notstand a power 
of over 50 diameters. 
5. Pin-hole diaphragm, could see 
nothing distinctly “a focus upon, 
— minutes exposu 
mpression on the alice plate. 
6. 'Pin-hole diaphragm, seven min- 
utes exposure, strong negative, 
but no fine details, 
7, Common glass lens, 6 inches fo- 
8 vo inch diaphragm, two min- 
tes exposure, view sharp, would 
stad 30 diameters, tolerably. 
stronger negative, and would not 
stand a mag ey ne power of 5 
diameters 
4, Twoanda a minutes exposure, 
+s inch diaphragm, no quicker 
action pee would only stand 
- a maguifying power of 4 or 5 di- 
5. Pin-bole diaphragm. Similar re- 
sult. 
6. Pin-hole diaphragm. Similar re 
sult, 
i i two minutes 
7. Jy inch ee it “on. quicker 
are ba not as sharp, owlDg 
possibly to a slight double refrac- 
tion in ia 
