138 
Fig. 4. 
If the rotation of the lens and the change of position of the 
plate be made with due regularity perfect definition is obtained, 
but the greatest accuracy is necessary to obtain this. 
To return to the history of this instrument. Mr. Martens 
by a note to the Academy registered the fact of having pro- 
duced views in this manner, and his instrument was laid aside 
until it was disinterred for the first time we believe last sum- 
mer. As far as we are informed, although Mr. Martens has 
yearly produced splendid views of Swiss scenery and has 
regularly published them, yet no product of the machine has 
been shown by him since 1854, the elaborately engraved 
panoramas of the Swiss alps having been produced by laying 
views taken by the ordinary camera side by side, and copying 
them juxtaposed. 
Various other gentlemen subsequently undertook to solve 
the problem. Among others may be mentioned M. Garella, 
an engineer officer employed in Algeria; Mr. Sutton, so well 
known for his high attainments and inventive talent; Mr. 
Hosmer, &c. 
The plans of these gentlemen have been published. Other 
plans have been heard of, as those of Mr. Rawlinson, of Kes- 
wick ; Mr. Stuart, an Indian officer — but those plans have 
not been made known. 
It would be an interesting subject to examine all these 
projects in detail, but to understand them would require 
numerous diagrams and perhaps models. 
In general terms it may be stated that all of those known, 
including that of Martens, possessed two features which render 
