Of OXFO %T)^S H I \E. ^3 
to Egypt. Encelr^^ ' thinks it a fort of moifture of the earth, fo 
concreted, that like ^r/^rj//?^:/ it will notdiflblve, but remains as 
it were an indiifolubie Ice^ whence the Germans took occafion to 
call it Glacies MarU. But that learned and induftrious inveftiga- 
tor of Nature, Gtorgiu^ Agricola^ differs from them all, and makes 
itaproduftof Lime-fiom and water^ Gignitur (fays he) e:Kfa\o 
calcps cumpauca aqua permifio " ; and thus I find it to grow here 
with us at Heddington^ in a blue clay that lies over the Quarry, 
whofe outermoft cruft is a hard Lime-ftone. 
10. The learned and ingenious Steno^ in his Prodromu^^ thinks 
ChrjftalU and Stknius\, and all other Bodies having a fmooth 
furface to have been already hardened, when the matter of the 
Earth, or flones containing them, was yet a fluid ; if fo, indeed 
Agrkola muft be out in his aim. But I cannot fee how our bed 
of clay zz Heddington^ above the Quarry at fome places ten foot 
thick, could have been a fluid within fome ages paft ; and yet of 
thtSelenites'sof the Rhomboideal ¥igme^ I find fome as fmall as a 
Barley-corn fome about three inches, and others again at leail 
half a foot long : fo that they feem rather to have fome fucceffion 
of growth, and now to be in Jieri ; than to have been all together 
already hardened, when the clay that now contains them was but 
a fiuid. Belide, they then would have been found clofe together, 
whereas we here meet them fome higher fome lower, and mix'd . 
all together little and great ; and the very clay it felf,as 'tis' broken 
to pieces, feeming fomwhat inclinable to this fort of form. 
1 1. A third fort we have of them alfo found here at Hedding- 
ton^ in the very fame clay, as alfo at Cornwell and Hanwell ; with 
two fides like the former, more deprefled then the other, in com- 
pafs alfo hexangular (thethineft fides of them being divided by a 
ridge) but in the form, not of a Rhomboid^ but ?a\ inequilateral 
parallelogram^ zsinTab. 2. Fig. d^. Some of thefewefind 
fingle, lying in any pofture, the biggeft fcarce aa inch inroad, or 
above four inches long ; and others joined together in a certain 
pofition, with their flatteft fides towards each other, and edges 
downward, and their ends conftantly meeting in a center. The 
Ingenious Sir Thomas Pennyfton has obferved,that at Cornwell they 
generally lye in ternaries^ but here at Heddington we find them 
t De Lapidibas (^G?7nmis, lit. T^. cap. ^6- u De Natura Fojfilium, lib. 5. vt Vrodromi prop. i. obfer- 
vat» !• *liheiea.\:elacha.sihei^£mSpaifi,ThuriKpa,a.ndCappa£locta% Aldrovand, lil>.i^. cap- 1^. 
L 2 often- 
