and Description of the Eidograph. 429 
known ; for besides occasional applications to the construction of 
enlarged maps and scientific diagrams, exhibited in the meetings 
of this Society, and to other purposes of public utility, it has 
been extensively employed by some engravers in constructing 
drawings for the plates of literary undertakings, and in particu- 
lar, the seventh edition of the Encyclopedia Britannica, now in 
course of publication ; to the anatomical engravings of which, as 
well as to those of other works of a like kind published in Edin- 
burgh, it has given a degree of perfection much beyond what could 
have been attained without its aid. 
I am sorry to have reason to say, that at least one imitation 
of my instrument has been pressed on public attention, in oppo- 
sition to mine, which, for an obvious reason, has been disparaged 
by comparison with the imitation. I possess, however, in wri- 
ting the testimony of competent judges that, the defects alleged 
to be in my instrument really did not exist. In fact, the imita- 
tion isa modification of the first form that occurred to me, but 
which was abandoned for a better. My case, however, is no 
worse than that of many inventors : their labours have frequent- 
ly been imitated after they have been at great pains and expense 
in bringing them to some degree of perfection. 
The Eidograph has been shewn to every ingenious person 
who has visited me since 1821, amongst whom have been many 
foreigners. This has been done in order to spread a knowledge 
of the invention, and to make it, if possible, useful to society ; and 
I have had the satisfaction of knowing that an imitation of it has 
been publicly exhibited amongst works of ingenuity in Russia 
by a British officer, who, however, had the candour to acknow- 
ledge to my friend who saw it, that it really was an imitation of 
my instrument. 
I shall now state some of the advantages which the graphic 
art may derive from the Eidograph. 
1. The instrument is applicable to the copying and reducing 
of very nice works of design; for example, the lineaments of a 
portrait. Indeed, it has actually been applied to the tracing re- 
312 
