NOTES AND QUERIES. 121 
established that when we are near the limits of “resolution,” the 
superiority of photographic vision, so to speak, over that of ordinary 
microscopic vision is as five to four, all other things being equal ; 
but it must be remembered that ordinary microscopic powers are 
constructed for vision and not for chemical portraiture. 
The various magnifications obtained by the several powers are set 
down by Mr. Davis as follows. At thirty-six inches :— 
Aine = 1X) 112 AS Ink =) X_-R 73 
1 
25> 9 » 21 2S Sere op tire. 
Ly Soy op. Si eS 990199" 093 530 
aes So 
DA ae ”? 9 
Bibliography.—Dr. Beale’s How to Work with the Microscope ; 
Monthly Microscopical Journal: report by Dr. Woodward, vol. vi., 
p- 169; Quarterly Journal of the Microscopical Society, vol. i., 1853; 
Northern Microscopist : article by G. E. Davis, April, 1881 ; Sczence 
Gossip, 1876: article by F. H. Powell; Zhe British Journal of 
Photography, January 26 and February 2, 1883 ; English Mechanic, 
February 2, 1883. 
In conclusion: before we show upon the screen some of the 
combined work of Mr. Pollitt and myself, allow me to admit that 
in the presence of such an important Society I feel I have much 
more to learn than to teach, and I invite your candid criticism of 
any statement I have made with a view to furthering the develop- 
ment of a most interesting branch of your art, which for some years 
has been a source of much interest to myself, and is evidently about 
to become of great educational value. 
NOTES AND QUERIES. 
Att Notes and Queries should be sent to Mr. George E. Davis, 
The Willows, Fallowfield, Manchester, before the 16th of 
each month. 
SUBSCRIPTIONS FOR 1883. The current year’s subscriptions became 
due in January last. Will those subscribers who have not re- 
mitted, kindly do so at once? 
Bacittus TuBEeRcuLosis.—Mr. Coppock, in sending out his 
prepared stains, issues the following directions for staining and 
preparing sputum :— 
“Obtain fresh sputum, and spread a small portion upon a thin 
cover glass, dry in the air, place a few drops of the Magenta and 
Aniline Stain in a watch glass and float the cover glass, sputum 
