JDescr'iption of the Opligraph. 67 



pencil : bul so tedious is the operation, and great the difficulty, . 

 of representing objects in true perspective, that they trust 

 mostly to their eye and experience For success. The result of 

 such a mode of proceeding maybe determined by portraits 

 drawn by the best artists, and the different judgments formed 

 concerning them. It has been well observed, that there is 

 no artist who will be hardy enough to say that he can deli- 

 neate by the eye the same object twice with exactness, and 

 preserve a just and similar proportion of parts in each. In 

 one of the figures we shall find some of the parts larger than 

 in the other; both cannot be right: yet supposing them 

 perfectly the same, neither may be conformable to nature. 

 In addition to this, many situations of an object occur, 

 which no eye, however habituated, can represent with ac- 

 curacy. 



On this account many attempts and various instruments 

 have been made for the purpose of giving the outline of an 

 object with accuracy. 



The late most ingenious Mr. Ramsden, so well known 

 for his inventions and improvements in various instruments, 

 considered the present subject an object worthy of his atten- 

 tion, and invented the instrument I am about to describe, 

 which is so simple and easy in its operation, that a person 

 not possessed of the least knowledge of drawing, may, with 

 less th'an three minute-;' instruction, be perfectly able to take 

 a perspective view of landscape, building, machinery, or, 

 in fact, an object of any description presented to his eye, 

 with the utmost correctness. 



Mr. Ramsden left this instrument without the means of 

 enablinc: the operator to enlarge or diminish his drawing; 

 an inconvenience which T have obviated, while at the same 

 time I have added some other trifling improvements. Thisin- 

 Btrumeni is certainly superior to any hitherto constructed for 

 the same purpose ; for in this the operator views the object 

 through a telescope, which enables him to delineate minute 

 objects with great exactness and ease, which arc often too 

 far from the eye to be sceu sufficiently well to be dtlincaled 

 correctly. 



E 2 Fig. I . 



