On the Kaleidoscope. 379 



" But that the fourth figure may yet be more intelligible and 

 useful, I have drawn on every side of it a scale divided into equal 

 parts, by which means we may ascertain the just proportion of 

 any design we shall meet with in it. 



" I have also marked every side of the fourth figure with a 

 letter, as A B C D, the better to inform the reader of the use of 

 the invention, and put him in the way to find out every design 

 contained in that figure. 



" Exp. 1. Turn the side A to any certain point, either to 

 the north or to the window of your room, and when you have 

 opened your glasses to an exact square, set one of them on the 

 line of the side D, and the other on the line of the side C ; you 

 will then have a square figure four times as big as the engraved 

 design in the plate ; but if that representation should not be 

 agreeable, move the glass (still open to a square) to the No. 5 

 of the side D, so wiil one of them be parallel to D, and the other 

 stand upon the line of the side C : your first design will then be 

 varied; and so by moving yom- glasses in like manner from point 

 to point, the draughts will differ every variation of the glasses, 

 till you have discovered at least fifty plans differing from one an- 

 other. 



'•' Exp. 2. Turn the side marked B of the fourth figure to 

 the same point where A was before, and by moving your glasses 

 as you did in former example, you will discover as great a va- 

 riety of designs as had been observed in the foregoing experi- 

 ment : then turn the side C to the place of B, and managing 

 the glasses in the manner 1 have directed in first example, you 

 may have a great variety of different plans which were not in 

 the former trials ; and the fourth, D, must be managed in the 

 same manner with the others; so that from one plan alone, not 

 exceeding the bigness of a man's hand, we may vary the figure at 

 least 200 times ; and so consequently from five figures of the like 

 nature we might show about 1000 different sorts of garden plats; 

 and if it should happen that the reader has any number of plans 

 for parterres or wilderness works by him, he may by this method 

 alter them at his pleasure, and produce such inmmierable varieties 

 that it is not possible the most able designer could ever have 

 contrived. 



"And seeing I have given such directions as I hope may inform 

 the curious of the use of this new invented instrument, I think 

 it may not be improper to advertise that the publisher of these 

 papers is provided with glasses of several sizes ready fitted up for 

 the experiment, at the following prices: the smaller sort atjSf. 

 and the other at 55." 



In the foregoing description of Bradley's invention, the prin- 

 ciple of reflection on which he constructs it, is precisely that 



which 



