[ 2 75 ] 
but would be found only on the under Part of that 
Shoot, where its own Gravity would inevitably carry 
it : For it would be obferved immediately, that thefc 
Diamonds in the Mine point forth in all Directions 5 
which mud confequently prevent every unimpreg- 
nated | ulcc from hardening into a regular uniform 
Sheath. 
It is alfo to be noted, that thefe Sheaths are often 
found broke and interrupted : But this cannot be 
owing to their being Gemma inchoata & non per- 
feEta (27), for the above-mentioned Reafons, but to 
the Infufficiency and Want of Juice, or to fomc ac- 
cidental Impediments of Stone, Earth, or Sand, which 
make thofc Breaks, and prevent it from forming a 
complete Sheath. 
Sect. <?. 
Of their Direction in the Mine. 
Not long fince I went with a Friend or two into a 
Mine called Pillion Erth, in the Parifh of St. Juft, 
on purpofe to furvey the Cornijh Cryftals in their na- 
tural Situation. The Cave, to which we were intro- 
duced, was not much larger than a common Baker’s 
Oven, and much of that Figure. We had two Candles 
with us, by means of which we faw the Roof, which 
might, in the Middle, be about five Feet high from 
the Floor ; in the other Parts not fo much. The 
Roof was the mod furpriflng Piece of Fretwork ima- 
ginable, and confided intirely of Spar fhot into Cormfh 
Diamonds, of which the large one (Fig. 16. TabV.) 
was a Part. I could not difeern any coveting a Poftion 
Mm2 exactly 
(27) As Tiot-) ibid, ut fupra. 
