424 Prof. Wallace on the Invention of the Pantograph^ 



I had recourse to iron rods. These, however, it was difficult to 

 get of the requisite straightness, while to connect them by joints 

 convenient for motion seemed impossible. I consequently put 

 them away, and betook me to rods of wood. 



" Placing one of these before my thoughts, I supposed it per- 

 forated at certain distances, and hollowed out \ with this, so fitted 

 for use, I found out something regarding the motion round the 

 centre, but with regard to that to and from the centre, it proved 

 to little purpose. Next I joined two rods, using their common 

 junction as a moving centre, and assuming a point, which might 

 be in either, as a fixed centre ; but neither in this way did I at- 

 tain my object. At length, making an attempt with four rods, 

 forming a gnomon round a small parallelogram, I began to con- 

 ceive better hopes of success. However, owing to placing the 

 tracer and drawing pen almost always on the same rod, or in a 

 position deviating beyond the straight line, I did not reach the 

 desired end on the first day that I entered on the inquiry. The 

 object of this invention related to the producing a copy broader 

 than the original, but in what manner to perform corresponding- 

 ly what referred to the height greatly perplexed me. I had, 

 indeed, learned how to go round the fixed centre, but I was un- 

 certain as to the method either of receding from, or approaching 

 to it. However, I did not despair, but after some consideration, 

 I resumed the design of accomplishing the work at the hours and 

 days of my leisure ; telling nothing to any one of my attempt, 

 but sedulously commending it to God and my guardian genius. 



" These at last were not wanting to my arduous efforts, but 

 most graciously imparted a knowledge of the whole secret, along 

 with its scientific principles, on that same night which precedes 

 the day sacred to Saints Fabian and Sebastian. In this reve- 

 lation, the form itself of the instrument was so represented 

 to my mind, its practice, and a demonstration of the whole 

 shewn, as it were, at one glance, as if I had seen all things 

 with my bodily eyes, and was receiving the lesson of a master 



