2^0 The Statural Hijlofy 
ftands higher or lower in the Glafs, weighs unequally on the air^ 
and gives it a contraftion and extenfidn, befide what is produced 
by heat znd cold ; he therefore invented a Circular 7hemomttei\ in 
which i\\t liquor can occafion no fuch fallacy, it remaining conti- 
nually of one height^znd moving the whole inftrument like a wheel 
on its axel \ 
36. hmong^ oihtt J erotechnicks-y here is a Clock lately con- 
trived by the ingenious /oy^;? Jones LL. B. and Fellow of Jefu^ 
College Oxon: which moves by the ^ir, equally expreffed out of 
bellows of a cylindrical form, falling into folds in its defcent, 
much after the manner of Paper Lanterns : Thcfe, in place of 
drawii gup the weights of other Clocks^ are only filled with air^ 
admitted into them at a large orifice at the top, which is ftop'd 
up again as foon as they are full with a hollow fcrew^ in the head 
whereof there is fee a i'm^ll brafsplate^ about thebignefs of a fil- 
ver half penny, with a hole perforated fcarce fo big as the fmal- 
Icfl: pins head : through this little hole the air is equally expref- 
fed by weights laid on tl e top of the bellows^ which defcending 
very (lowly, draw a Clockrline^ having a counterpoife at the o- 
ther end, that turns a pully-wheel, faftened to the arbor or axis 
of the /'jw^ that points to the ter : which device, though not 
brought to the intended perfection of the Inventor, that perhaps 
it may be by the help of a tumbrel or fufie^yet highly defei ves men- 
tioning, there being nothing of this nature that 1 can find amongft 
the writers of Mecbanickj, 
37. To which may be added, a hopeful improvernent of that 
uncommon Hygrofcope^ made of two Deal^ or rather Poplar hoards^ 
mention'd in our Englidi Fhilofophical Tran[a5iicns^^ contrived, 
by my ingenious Friend j^ohn Toung M. A. of Magdalen Hall^ who 
rationally concluding, that the teeth of the thin piece of brafs 
placed acrofs thejunfture of the two boards^ mud needs in its 
paifage from bearing on one fide of the teetb of the pinion, to the 
other, upon change of weather, make a ftand as it were in re- 
fpeft of the motion of the axel of the hand ; thinks a pretty ftifF 
/pring cut on the under fide, after the manner of a fine //e, placed 
flat and not edge-ways, and bearing pretty hard upon an axel or 
Copper^ may turn the hand upon change of weather in the punSlum 
of reverfion, without any more than a negative reft : which he^ 
' Hiftory of [he Royal Society, /tfr/. 2. ' Philofoph. Tranfadt. Nww^ 127. 
ing 
