i88 UE M O I R S of the 
great many hills thrown up, called Sin'rozvSy luppofed to be fe- 
pukhral monumenrs. 
j4 Water Microscope; by ^/r. Stephen Gray. Phil. Tranf. 
N° .2 5- P- 5 5 5- 
AB Fic^. I. Plate VI. is the frame of the microlcopc; it may 
be about To of an inch in thickncfs j at A is a jiTiall hole, 
near ;o of an inch diameter, which ferves for the aperture of the 
water, in the centre of a larger fphcrical cavity, about -f of an 
inch diameter, and in depth lomewhat more than half the thick- 
ncis of the brais ; opposite to thi.s, at the other fide, is another 
concave, only half the breadth of the former, which is io deep, 
as to reduce the circumference of the Imall hole in the centre to 
almofl a iliarp edg^ ; in thefe cavities the water is to be placed, 
being taken up on a pin, or large needle, and conveyed into them 
till there is formed a double convex lens of water, which, by the 
concaves being of different diameters, will be equivalent to a dou- 
ble convex of unequal convexities; by this means, the objc6t is 
rendrcd more diftinfl than by a piano- convex of water, or by a 
double one, formed on the plain furface of the metal; CDE is 
the fupporter, whereon to place the objeft; if it be water, in the 
hole G; if a folid objefl, on the point F; this is fixed to the 
frame of the microlcope by the icrew E, where it is bent up- 
wards, that its upper p^rt m^y ifand at a diftance from the 
frame; it is moveable on the Iciew as a centre, to the end that 
either the hole C, or the point F, may be expofcd to the micro- 
fcope, and that the object may be brought to, and fixed in its 
Focus, There is another Icrew, about half an inch in length, 
which goes thro' the round plate into the frame of the microlcope 
A £, the fcrew and pL.te taking hold of the fupporter about D, 
where there is a flit, ibmewhat larger th.in the diameter of the 
Icrew, which is requiiite for the admiflion of the hole C, or 
point F, according to the nature of the object, into the For us of 
the glals ; for by turning the fcrew G, the lijpporrer is carried to, 
or from the famiC; which may be fooner done, if whilft one turns 
the fcrew with one hand, the other hold the microlcope by the 
end B, and one continue looking thro' the water till the objeft be 
feen mod diflinclly. The lupporter mufl be made of a thin 
piece of brafs well hammered, that, by its fpring, it may the 
beticr fellow the motion of the fcrew ; Mr. Gray chole rather to 
iix the Ir.pportcr by the ic.-cw K, than by a rivet; becaule it may 
now, by means of a knife, be unlcrcwed, and by the other fcrew 
G, be bro-jght clofe to the frame of the microlcope without 
weak- 
