76 
can scarcely be read, but it can be seen that only greater 
power is required to make the whole legible. It happens 
that the covering glass is very thick so that powers higher 
than the eighth cannot be used. It will be noticed that 
the name W. Webb, 1863, is distinctly legible and very beauti^ 
fully written. 
Mr. Armstrong has given me some particulars of Webb’s 
minute writing from which it appears that he was accus- 
tomed to write the Lord’s Prayer in spaces of the 500th 
to the 10, 000th of an inch, and as we have seen to the 
405,000th and the prices of these slides varied from 2s. 6d. 
to 70s. 
Corrigenda. 
Page 8, lines 13 and 22 : for complimentary read 
complementary. 
