154 Chronicles of Science. | Jan. 
VIII. PHOTOGRAPHY. 
By far the most important subject which has arisen in this branch 
during the last quarter, or, indeed, for many years past, is the alleged 
discovery of photographs taken half a century before the recognized 
birth of this art. An immense mass of evidence, direct and collateral, 
has been collected together in the most conscientious and energetic 
manner by Mr. Smith, Curator of the Patent Museum, and it certainly 
affords strong grounds for the presumption that no less than three, if 
not four, distinct classes of pictures, each by a different process, pro- 
duced about the year 1790, are now in existence, there being the 
strongest circumstantial evidence that they are bond fide photographs. 
One is on a silver plate, pronounced by leading members of the Pho- 
tographic Society to be an undoubted photograph from nature, the 
subject being Mr. Boulton’s house, which was pulled down in 1791; 
the picture was found amongst papers in Mr. Boulton’s library, which 
had not been disturbed during the present century. There are also 
two pictures—one of them undeniably a photograph—which were 
found by Miss Meteyard amongst papers supplied to her for the 
purpose of writing a life of Wedgwood, the great potter; and from 
documents of that date they are said to have been produced by the 
younger Wedgwood, reference being made to a lens, camera, and 
chemicals. There is also the hearsay evidence of an old retainer of 
the Boulton family, lately dead, of the silver picture of Mr. Boulton’s 
house having been taken by placing a camera on the lawn; and there 
was a society called the ‘ Lunar Society,’ the members of which were 
said to produce pictures by using a dark room, throwing the images 
on to a table, and fixing them by some chemical. The whole subject 
has recently been brought before the Photographic Society, and, on a 
careful analysis of the evidence, there is the very strongest presump- 
tion, short of absolute certainty, that this important discovery was 
made, and then suffered to die out. Only a few links in the chain are 
wanting to establish the actual proof, and from the intense excitement 
the subject has now occasioned, there is little doubt that it will be 
sifted to the bottom. 
The measurement of the chemical action of light has lately received 
considerable attention. Dr. Phipson* has published a process which 
appears to promise very good results ; it is based upon the fact, that a 
solution of sulphate of molybdic acid is reduced by the action of light 
to a lower state of oxidation ; and by measuring this amount of reduc- 
tion by chemical means, a correct estimate of the amount of actinism 
used up in the operation is obtained. The measurement is done with 
a standard solution of permanganate of potash; and Dr. Phipson 
states that his observations have disclosed the fact, that the amount of 
actinism during the day varies considerably, describing curves, which 
are not only irregular, but sometimes present sudden deflections of 
considerable extent. This phenomenon has been noticed before. 
During the last summer many correspondents of the ‘ Photographic 
* «Chemical News,’ vol. viii. p. 135. 
