224 
Communications made to the Society: 
(1) On an illustration of the empirical theory of Vision. 
By Mr Courts Trottsr. 
Mr TROTTER gave an account of some experiments which he 
had made. With one eye he was shortsighted, the other had 
the ordinary range of vision. On using spectacles with one 
glass concave and the other plane, so as to bring the defective 
eye up to the normal range without altering that of the other, 
he found some difficulty in judging distances, &c. Thus when 
both his eyes had the same focal length, and were thus both 
perfect instruments, he did not see so accurately as when one 
of them was an imperfect instrument. Hence he contended 
that the result of his experiments supported the empirical 
theory of vision. 
(2) On a Table of the Logarithms of the first 250 
Bernoulli Numbers. By Mr Guaisuzr. 
Mr Glaisher’s communication was not of a nature to be 
given in abstract. 
