VOL. XXVII.] PHILOSOPHICAL TRANSACTIONS. 551. 



English silver were not so transparent as the other; and that this silver, which is 

 supposed to be allayed with a 12th part of copper, tinges the water of a very 

 green colour, and leaves a great deal of dross at the bottom. I observed also 

 in the same water, some few of the long crystalline particles, which had six 

 sides, and ended in two points of the same figure, like the particles of rock, 

 crystal, only that most of them have but one hexangular point ; the reason of 

 which I suppose to be, that the other end is fastened to the rock. And as this 

 appeared strange, I examined again some of those diamond crystalline particles, 

 which were lying by me; and discovered among them, but in a very small 

 number, some of the last mentioned figures, which are here represented in 

 fig. 6. And I suppose, that all the mountain crystal would be of the same 

 form, if the rocks and stones, among which it is found, did not prevent it, 

 while soft. I also observed one six-sided figure, which only differed from the 

 preceding, that one side of it was at least twice as broad as its opposite ; by 

 which means the hexangular point was askew, as it stands in fig. 7* 



Fig. 8 represents also another small crystalline particle, which was of the 

 same figure as the former in its sides, and at one end ; but the other end was 

 not hexangular, but of the shape of a hatchet. In the middle of the same 

 figure, there appeared a break, or rent, which seemed as if it had been two 

 distinct particles, joined together as they grew, till they became one body ; yet 

 still retaining the marks of their joining, as seen in the figure. 



On the Manner of making Microscopes, &c. By Dr. Archibald Adams. 



N° 325, p. 24. 



I think that all the microscopes which preceded Mr. Leuwenhoeck's, are so 

 much outdone by his, that it will be proper only to take notice of these and the 

 rest of later invention. 



I had not an opportunity of examining Mr. Leuwenhoeck's glasses parti- 

 cularly, which is a favour he allows to none ; therefore I am not capable of de- 

 scribing either their make or use, any further than that they appeared to be 

 spherules lodged between two plates of gold or brass, in a hole whose diameter 

 might not be larger than that of a small pin's head, and the objects I saw 

 through them were pretty and diverting ; but still their make and truth are un- 

 known. 



Mr. Butterfield is very curious in melting his glass, but I suppose unsuccess- 

 ful in casting his spheres ; for besides that a sufficient quantity of beaten glass 

 cannot stick to the moistened point of a fine needle ; so neither can it run 

 equally, hold the needle how you will, nor the globule when run stick to the 



