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fcafrow fide, againft which there is no bone, as ob- 
ferved before: fometimes it is preffed out only in 
part ; and this, together with the fpherical part, is 
fill'd up, probably at firb with the floating matter i 
which, I luppofe, when the other bone was formed 
upon it, fo united with it, that it remains as a part 
of the other bone, and breaks off from it, when 
they are moved : and if this happened to the lower 
part of the upper done, this matter, which fills up, 
might unite with the lower done ; for fometimes this 
narrow fide is feen in the fame done both above and 
below, the angle being formed in the middle of the 
done ; and then it is filled up with the matter, which 
united with the done above, and the done below. 
It is to be obferved, in purfuance of the proof, that 
the dones were originally round, and fpherical at the 
ends ; that when the predure was not fufficient to 
make out the angles, which I fuppofe to be the caofe. 
of thefe narrow fides, it is in tins cafe plainly feen, 
that the original circular diape of the done is dill 
retain’d ; that dde not being horizontally in a drait 
line, but appearing plainly to be part of a circle ; as 
may be feen in the three pieces of done, which 1 have 
fent, that feparated from thole fides, and fitted into 
them. 
It appears alfo, that what has been prefs’d out be- 
yond the circle at the ends is commonly flat, and not 
concave and convex ; as it w r as probably made, not 
by the prefiure at the ends on the fpherical part, but 
by the prediire on the fides contiguous to it ; and 
when part of the circle is taken off, in that cafe it is 
probable, that the preffure on the fides was very great. 
In one done, the matter, which only in part form’d 
the angle, force being applied to it, came ob', and 
2 left 
