113 
Dr. Carpenter, on Stereoscopic Binoculars . 
the advantages of the Binocular to the Continental (especially German) 
savans who -have not made themselves acquainted with the instrument. 
And he has been struck with finding that when he exhibited to them objects 
with which they had previously become familiar by careful study, and of 
whose solid forms they had already attained an accurate conception, they 
perceived no advantage in the Stereoscopic combination ; seeing such objects 
with it (visually) just as they had been previously accustomed to see them 
(mentally) without it. But when he has exhibited to them suitable objects 
with which they had not been previously familiarised, and has caused them 
to look at these in the first instance monocularly y and then stereoscopically , 
he has never failed to satisfy them of the value of the latter method, except 
when some visual imperfection has prevented them from properly appre- 
ciating it. He may mention that he has found the wing of a small Butterfly, 
having an undulating surface, on which the scales are set at various angles 
instead of having the usual imbricated arrangement, a peculiarly appropriate 
object for this demonstration ; the general inequality of its surface, and the 
individual obliquities of its scales, being at once shown by the Binocular, 
with a force and completeness which could not be obtained by the most 
prolonged and careful Monocular study. 
