GEM S.. ? 
. Next he models the subject in wax, as delicate. 
> ‘as possible, which he means to » in order 
of ‘that he may constantly avail himself of the resemblance, 
*~> or he has some other subject which he is to imitate 
‘before him. His tools are few and simple, consisting 
of a lathe nearly on the same principle as the turning 
Jathe, into the end of the spindle of which he can in- 
‘sert points, knobs, or circles. These project a certain 
distance, and receive a rapid motion from a wheel be- 
low. The gem is fixed with mastic-to the end of 
a small piece of wood as a handle, and the ernie 9 
the subject upon it with a copper point or a diamond. 
It iethen & hiied to the end of ses the tools in mo- 
tion, which, being wet with diamond dust and olive 
oil, quickly grinds off the surface; and, by long per- 
verance, or frequent repetition, produces the outline 
the figure, and thet. the hollow or relief. Frequent 
impressions must be taken in the course of the work, 
to shew where there is any excess or defect ; for the 
slightest error in one part, may occasion the alteration 
of the whole. Stich impressions, however, are neces- 
sary only in intaglios, * not in cameos, because both the 
prominences and depressionsare there obvious tothe eye; 
and éxperienced artists consider it more easy to work on a 
convex surface, from the distance interposed between 
the tool and the hand. rR the most elegant 
curves may be produced with skill and attention, much 
diffieulty is experienced in cutting angles; for the tool 
bei e segment of a circle, can never be closely ap- 
“plied ; and hence all the letters on the ancient gems, 
even of the first masters, are imperfect. 
The tools employed are either of soft irom or copper ; 
and in defect of diamond powder, that of the ruby, or 
other hard stones, may ber ecbetituted. In cutting 
the amethyst, the Bohemian emerald, or crystal, wa- 
ter is used to wet the diamond dust instead of oil. 
Tools of still softer metal, along with tripoli, or rotten 
stone, and lastly brushes, are used in giving’ gems 
their final polish ; but it has been observed, that, in 
this respect, the moderns have never been able to equal 
the ancients. We describe this process in few words, 
but it is a slow and tedious operation, and requires a pe- 
netrating eye, and a delicate hand. Theartist must be 
master of drawing and modelling, and he must be a suf- 
‘ficient naturalist to be intimately acquainted with the 
ies and im ions of the various finer stones. 
Ithough the art of engraving might have been 
ed during the darker ages, it is doubtful whe- 
‘ther the method of giving impressions to paste, with- 
‘out engraving, was not entirely lost. It was revi- 
‘ved, however, by M. Homberg, who, in the year 1712, 
oe it in such a manmer, that ali later ar- 
‘tists have been enabled to follow his precepts. A 
quantity of soft, smooth, red tripoli is pounded in an 
iron mortar, sifted through a fine silk sieve, and set 
aside for use. Another species, called yellow, or Ve- 
netian tripoli, which has a natural kind of unctuosity, 
is then with a knife, and bruised in a glass 
mortar, with a glass pestle, until reduced to a very fine 
powder ; the finer it ts the more favourable for the im- 
pression. The red tripoli is now to be mixed to the like 
consistence of with water, and when moulded 
“between the fingers; it is put into a small flattish cru- 
cible, scarcely exceeding half’an mch in depth, and 
_ little morein breadth at the surface than the size of 
the gem, whose peng is to be taken.* The cruci- 
ble is then to be filled with the paste, slightly pressed 
down into it, and the dry yellow tripoli strewed over 
“its surface. Here the stone which’ is to give the im- 
“pression must be laid, and pressed down so much on 
129 
the paste, as to give it a oh, Spe and perfect im- 
pression ; and the tripoli is to 
nicely to the edges, with the fingers or an ivory knife. 
After the stone has lain a few seconds to allow the humi- 
dity of the paste to moisten the dry powder of the yellow 
tripoli scattered over it, the operator must raise it eare- 
fully by a needle fixed in a wooden handle, and the 
crucible being inverted, it will fall out, while the im- 
pression remains on the tripoli still adhering to the 
erucible. The stone must now be examined, to ascer- 
tain that none of the paste has come off along with it, 
otherwise there will be a corresponding defect in the 
impression, and the operation must be ted. Ha- 
ving allowed the crucible and paste to dry, the artist 
selects a fictitious of the suitable size to be laid 
over the mould, but in such a manner as not to touch 
the impression, which would thus be obliterated or in- 
jured ; and the crucible being gradually brought near- 
er the furnace, is to be heated until it can no Jonger be 
touched by the hand, when it must be placed in the 
furnace under a muffle, surrounded with charcoal. 
When the gem begins to appear bright, it is the sign of 
being ready to receive the impression. The crucible 
must now be taken from the fire, and the hot gem pres- , 
sed down with an iron implement, to make it receive 
the impression from the mould below it ; after which 
the crucible is to be set by the side of the furnace, to 
cool «gradually without breaking. When cold, the 
gem may be removed, and its edges nipped or grated 
round with pincers, to prevent it from cracking, which 
sometimes happens. Red tripoliis used for the paste 
only from economy, as it is the yellow species alone 
which is adapted for the purpose. Casts of plaster of 
Paris may be substituted for both, made into small 
cakes half an inch thick, and being put into a furnace 
without a crucible, the gem is to be pressed down upon 
it to take the impression. 
Many discussions have arisen among the learned con- 
cerning the use of those ancient gems, now preserved 
with so much care in our cabinets. The beauty and ra- 
rity of natural jewels constitute their principal recom- 
mendation, and they have always been employed as 
personal ornaments, some being more prized than others, 
according to fashion or ideal properties. It has been 
suppose! that engraved gems were applied in the same 
manner, and purposely sculptured for ornaments. 
During some time, there was an ordonnance of 
the Roman emperors, prohibiting the use of rings 
bearing their portraits, the infringement of which was 
little Jess than a capital crime; and we are told of 
the pretor Paulus being exposed to imminent danger, 
from having a cameo representing the Emperor Tibe- 
rius. Mas om seo wisely removed this restriction, But 
the use of those elegant subjects of mythology and 
history, which appear in relief, is less evident, unless 
it had some relation to the religions principles of the 
owner, or was like a picture, designed to perpetuate 
historical events. It is said that the Romans long ab- 
stained from engraving any image of their gods on 
gems ; but adopting the religious fashions of other na- 
tions, they became enslaved by superstitions. Augustus 
sealed with the head of Alexander, and then substituted 
his own, engraved by Dioscorides. Before resorting to 
either, he had sealed with a sphynx, Nero is said to 
have had a seal pe ih with the subject of Apollo 
flaying Marsyas ; that of Pompey represented a lion 
holding a sword ; and the Emperor Galba retained the 
seal of his ancestors, representing a dog on the prow 
of a vessel. Sylla, proud of the capture of Jugurtha, 
caused a representation of the King Bocchus, deliver. 
** An intaglio may be raised into a cameo optically, and vice versa, by viewing it with a microscope which inverts objects. Ep. 
’ nm 
VOL. X¥. PART 4. 
collected and applied ““v-—” 
