SCIENTIFIC SUMMARY. 
513 
the views of Sir William Newton, and denounced as false to both art and 
nature those photographs which represented “ near and distant objects on the 
same plane ; backgrounds and foregrounds of equal intensity.” In the dis- 
cussion which followed these papers, party-feeling grew so high that the 
society in consequence lost many of its more valuable members. Sir William 
Newton said on behalf of the artists, “We do not want at all to interfere 
with the photographer, we want rather to assist him ; to give him artistic 
views as much as we possibly can, and we will take advantage of what he 
does for us. We are not scientific men, we have not time for it, but we want 
the aid of scientific gentlemen.” Sir Charles Eastlake also took part with 
his brethren of the brush, but did not appear to consider perfection of detail 
and unity of parts were in any degree inconsistent one with the other. 
Some years after, the question was again revived by another artist and 
photographer, Mr. A. H. Wall, and a discussion almost equally warm again 
arose. So far from arguing for putting the lens out of focus, Mr. Wall con- 
sidered there could be no softness without perfection of definition, inas- 
much as gradation could only depend upon completeness of parts. But he 
argued against that hardness which was miscalled sharpness, and showed that 
it was neither consistent with nature, art, nor scientific exactness. Since 
then, converts to the artistic side of the question have become so numerous 
that our leading opticians have found it worth their while to manufacture new 
lenses specially intended to distribute that intensity of focus which was 
formerly concentrated upon one plane only, and spread it in relative degrees 
over as many planes of distance as it will cover without losing its defining 
power too greatly. These are now our most popular lenses, and they are in 
great demand. In this brief historical review we may see that the paper 
M. Claudet read before the British Association, “ On a New Process for 
Equalizing the Definition of all the Planes of a Solid Figure, represented in 
a Photographic Picture,” was not only “ a day after the fair,” but advocated 
an old-fashioned, imperfect, and inexact means of getting certain effects for 
which we already have legitimate and suitable instruments. M. Claudet’s 
very unscientific process is simply that of allowing the front lens of a portrait 
combination to remain stationary during the exposure of the plate to light, 
while by means of a rack and pinion the back lens is moved at successive 
intervals the twentieth part of an inch. By this means all the planes of 
-distance within certain limits are supposed to be successively in and out of 
focus. But M. Claudet appears to have overlooked the fact that the action 
of the in focus and that of the out-of-focus planes are neither relative to 
their nearness or remoteness from the eye of the camera, nor calculated to 
equalize definition in all the planes of a solid figure represented in the photo- 
graph. The part first in focus is subjected to the action of the out-of-focus 
image during the time that the other parts are exposed to the changing 
images, and therefore must be more out of focus than the parts last exposed, 
which for the same reason must be most in focus. Artistic softness is not 
inconsistent with crispness of definition, nor with perfection of detail, to both 
of which M. Claudet’s process is opposed, although it certainly is with the 
concentrated intense sharpness due to the condensation of the image by the 
lens, and the opticians endeavour to secure for one plane all the defining 
power the glasses possess. There is another consideration to be noticed, and 
