34 Sir David Brewster on the Stereoscopic Relief 



acquainted, and requested him to obtain from his pupils copies 

 of each of the Chimenti drawings. We were thus furnished 

 with six copies of one of the Chimenti figures by a pupil* of the 

 School, which could not produce, by any combination of them 

 in the stereoscope, the effect of the Chimenti drawings. This 

 was the opinion of Professor Tait, who mentions the experiment 

 in the Number of the Photographic Journal referred to by Pro- 

 fessor Emerson, who ought in fairness to have told his readers 

 that the very experiment which he maintained could be made by 

 any one with a certain result, had been already carefully made 

 with the very opposite result. 



If Professor Emerson made the experiment himself, or had it 

 made by others, why has he not told us the precise effect that 

 was produced ? If it was only " the same kind of effect" as in the 

 Chimenti drawings, and not the same degree of effect, the experi- 

 ment was worthless. It might have been a stereoscopic leg, or 

 a stereoscopic arm, or a stereoscopic shoulder, or a stereoscopic 

 knee, or any other " kind of stereoscopic effect," without having 

 any resemblance to the actual degree of stereoscopic effect pro- 

 duced by the Chimenti drawings. 



As this question must be decided by experiment, we defy 

 Professor Emerson to produce one result in a hundred sketches 

 by different individuals in which the stereoscopic relief exists at 

 all, instead of being as perfect as in the drawings alluded to ; 

 and if he could produce this miraculous sketch, it would merely 

 prove that it was 99 chances to 1 that the stereoscopic relief pro- 

 duced by Chimenti was not accidental. 



But if Professor Emerson were to obtain many examples of the 

 production of relief by blunders in copying a drawing, this would 

 only prove that the relief we have been considering might be thus 

 produced, not that it was thus produced. An important ques- 

 tion in the history of science is not to be settled by such poor 

 logic as this. Many points must be considered before it is proved 

 that what might be produced actually was produced. 



The stereoscopic pictures have been preserved as the work of 

 Chimenti himself, and the historian of science will naturally ask 

 what led so eminent an artist to make so uninteresting a sketch 



* We had the sketches made by a pupil, to meet the gratuitous statement 

 that one of the Chimenti figures might have been a copy by one of his 

 pupils. It certainly might have been ; but the drawings have been handed 

 down to us as Chimenti' s, and we are not entitled to assume, for any par- 

 ticular purpose, that one of them is the work of a pupil. The existence of 

 two such drawings exactly similar to the eye, and placed as they are, is a 

 circumstance so remarkable, that we venture to say that no similar pair of 

 figures will be found, either in juxtaposition or singly, among the thousands 

 of drawings left by ancient and modern artists. 



