Mr. Bew on Blindnejs. ^ 177 
apartment I fit in; the furniture, &c. will, 
by the organs of vifion, be immediately prefenced 
to the mind of any ftranger who may call on me, 
fo that he will be able, in a moment, to recollect 
the whole whenever he repeats his vifit, to the fame 
place. This kind of information can only be ac¬ 
quired by the blind man, in confequence of the 
mod patient attention. He is to be led round 
the feveral parts of the room, his finger conduced 
to the furfaces of the furniture, pictures, &c. 
before he can poftibly form any idea with refpeCt 
to the place. But when, by means of the per¬ 
ceptions of touch, and a necefifary degree of 
information, he conceives a regular train of 
diftinguifliing ideas, his mind afiociates them, 
with fuch tenacity, that he feldom has occafion 
to repeat his inquiries. 
It is this accurate and retentive power of the 
memory, that enables the blind mathematician 
to make exaCt calculations and inferences ; to 
work problems in algebra, and in infinite feries ; 
to conceive, with precifion, the different effeCts 
that bodies muft produce to the fight, by their 
being nearer or farther off; by their moving 
in a ftraight or in an oblique line; and, that 
direCts his inveftigation with refpeCt to the prin¬ 
ciples of projection, and the various rules of 
perfpeCtive. 
It muft here be remarked, that though the 
blind man may conceive the properties of figure 
Vol. I. N and 
