426 Prof. Wallace on the Invention of the Pantograph, 



instruction, would ever have made so illustrious a discovery, 

 which in his opinion should have been kept secret, and not pro- 

 mulgated to be trodden under the feet of the vulgar. 



" He that had the commission from Mr Scheiner then return- 

 ed thanks in his name to the painter, for having, by so indus- 

 triously concealing his small invention, given occasion for the dis- 

 covery of a much greater ; and by denying a little gem, having 

 paved the way to lay open a concealed treasure : and also, that 

 whereas at one time he might, by the doing of a small good of- 

 fice, have bound his friend to him for ever, so by his refusal he 

 had raised him to the dignity of being a benefactor to the 

 whole world. He added farther, that the inventor would take 

 care that this divine blessing should not fall into contempt, by 

 too promiscuous an imparting of it. 



" After this I gave instructions to some friends and pupils upon 

 the subject, and having, after teaching of Humanity for four 

 years at Dillingen, returned to Ingoldstadt to pursue Theology, 

 I there also communicated the art to some others. At this time, 

 William Duke of Bavaria, a person well skilled in the art of 

 painting, hearing of the fame of my instrument, invited me to 

 Munich to exhibit it before him ; and so wonderfully was he 

 pleased with its niceness, its sureness, and facility of execution, 

 that he desired me to write a short description of the instrument 

 itself, and the manner of drawing a figure. 



" In requital of this service he paid me the compliment of 

 making known to me that curious artifice by which water is 

 raised and projected upward. In this method the air is extract- 

 ed by means of two wheels closely connected, and by the suction 

 thus produced, the water is first raised and afterwards impelled ; 

 the rationale of the experiment being nature's dread of a vacuum, 

 and the impenetrability of bodies. 



" Having now returned from Munich to Ingolstadt, I went 

 through the prescribed course of Theology and published my 

 thesis. Being then requested by my superiors to teach Mathe- 

 matics, I was sufficiently liberal in communicating a knowledge 



