( io6 ) 
Cryftallum iftaai in complura frufta confregi, 8c 
frufta microfcopiis applicavi ; difquirere volens num 
8c ilia ex liiperftratis fibi lamellis compofita efTent : 
qua ratione Adamantes magnitudinem mam adeptos 
efle dixi. Sed, tametfi perquifitionem iftam faepius 
iteraverini, ne tantillam quidem lamellam in iis depre- 
hendi. Iflud autem in Cryftallis, quas quidem prae 
manibus habebain, plerumque animadverti, in omni- 
bus earum lateribus, qu^ numero fena erant, tranf- 
verfas protendi lineolas, alias aliis fitu aliquantulum fu- 
periores ; tamquam fi illic, increfcentibus Cryftallis, 
ortae producftaeque fuiftent : qua ftiper re, quantum- 
cumque Cryftallorum numerum ante conftderaverim, 
atque confregeriin, numquam iple mihi fatisfacere potui. 
^elphls in Hollandidy 
Nov. xo. I71X. 
IV. An Account of an Optical Experiment made he-, 
fore the Royal Society, on Thurfday, Dec. 
6th, and repeated on the 13 th, 1722. Ey the 
<I(eVerend J. T. Defaguliers, L L. 2 ). K S. 
S I R Ifaac Newton., in his Optics, {B. i. Brop. i. 
Exp. X.) relates an Experiment made with a Card, 
or Paper, painted red on one half and blue on the 
other, which being enlighten’d by a Candle, the I- 
mage, by the Interpofition of a Lens, is fb projecfted 
on a white Paper, held on the other fide of the Lens, 
that the Place where the blue half appears diftind:, (or 
as the Opticians term it, the diftind Safe of the Image 
of the blue half) is much nearer to the Lens than the 
Place, of the Image of the red half. And this is made 
apparent 
