164 Mr. Bew on BUndnefs. 
and optics, were remarkably clear and intelligible. 
Fully aware of the difficulties young minds have 
to contend with, from the abftrufenefs in which 
the fubjedts of natural philofophy are ufually 
involved, his endeavours were fuccefsfully 
directed to obviate and remove thefe obftructionsj 
and to furnifh a method, at the fame time, 
comprehenfive, natural, and eafy to be under- 
ilood. 
Dr. Saunderfon’s fenfation of touch, as is ufual 
with blind people, was very exquifite ; and it 
was by means of this lenfe, that he acquired many 
of his principal ideas. He diftinguiflied, with 
aftonifhing nicety, the peculiar properties of 
bodies, that depended on the roughnefs or fmooth- 
nefs of their furfaces. A remarkable inftance 
is given of his nice accuracy in this refpedl. 
A feries of Roman medals, fome of which were 
true, and others falfe, were prefented to his 
touch. Dr. Saunderfon, by running his fingers 
over them, was foon able to dillinguifh the 
genuine antiques, from thofe that were counter¬ 
feited ; though the latter had been executed, 
with fuch exadlnefs of imitation, as to deceive 
a connoiffeur, who only judged by the eye. Bur, 
fays the profeffor, {C I, who had not that fenfe 
“ to trull to, could eafily feel a roughnefs in the 
<c new call, fufficient to drftinguifh them by.” 
The impreffion made by the approach of 
bodies nearer to him, or their being removed 
farther 
