428 Prof. Wallace on the Invention of the Pantograph, 



About the middle of July I shewed my friend Mr Jar dine 

 my first essay, a rough model made of wood. His favourable 

 opinion encouraged me to persevere, and I succeeded in contriv- 

 ing an instrument, which gave reason to expect that, when pro- 

 perly made, by its use any plan could be copied, of the same or 

 a smaller size, or even larger than the original, with as much ac- 

 curacy as a tracing point can be carried along a line. To dis- 

 tinguish the instrument from others designed for a like purpose, 

 I have called it an Eidograph, from the two Greek words, sidoc, 

 a form, and yguQa, I write. 



I next attempted to contrive another instrument that should 

 make a reversed copy, that is, such as would be shewn by the re- 

 flection of the original from a mirror. In this also I succeeded, 

 but the construction was more complicated than that of the 

 other. The object of the reversing instrument was to make a 

 trace, at once, on copper, with a view to the etching of any sub- 

 ject on a varnished ground. An engraver whom I consulted did 

 not think this form so necessary and likely to be so useful as the 

 other, and therefore the invention has not been followed out be- 

 yond the rough model ; which, however, serves to shew that the 

 thing is quite possible. By this second construction, which may 

 be applied also to make a direct copy, an instrument might be 

 made, by which a person sitting in one room may write at a con 

 siderable distance in another, notwithstanding intervening walls 

 or floors. I mention this, because cases may be imagined in 

 which it might be useful for persons in different parts of an esta- 

 blishment to have the power of holding intercourse by writing, 

 without moving from their places. 



I shall not trouble the Society with a detail of the pains I 

 have taken to improve the Eidograph, and of my experience of 

 that law of the human mind, by which it tenaciously adheres to 

 old habits and methods to which it has been accustomed, and re- 

 fuses to adopt new ones, although more perfect. My object in 

 this paper is to prevent an useful invention from being lost, by 

 having it recorded. Indeed, its utility is now pretty generally 



