THE 
MONTHLY MICROSCOPICAL JOURNAL. 
DECEMBER 1, 1876. 
I. — On a New Method of Measuring and Recording the Bands 
in the Sjpectrum. By Thomas Palmer, B.Sc. 
{Read before the Koyal Microscopical Soclety, October 4, 1876.) 
Plate CLXI. 
The attention of workers at the micro-spectroscope has been now 
for some considerable time engaged in endeavouring to find out 
some more practical method of measuring and recording those 
spectra which are seen : to meet all the numerous requirements 
seems almost impossible. Taking, however, into consideration the 
short space of time that has elapsed since the adaptation of the 
spectroscope to the microscope, and the extreme difiiculty which 
the whole subject presents, you will all perhaps agree with me that 
a great deal has been done ; in some instances, I am afraid, how- 
ever, in a somewhat mistaken direction, for a measure, if it is to be 
worth much, must act alike in everyone's instrument, so that a 
certain formula may be set down for each band in question. This, 
I am quite aware, is a very high standard of perfection ; but that 
can surely be no reason for asserting that it is not to be reached. 
Many of you will agree with me when I say that our worthy 
President's, Mr. Sorby's, new method is near, at least at present, to 
that point ; but the quartz block, as perhaps you all know, is so 
extremely difficult to get right ; still the principle is correct, viz. 
that though a position is taken by the micrometer, the reference to 
and actual measurement of a band is in wave-lengths. This is what 
struck me just after I had heard Mr. Sorby's paper, and, besides 
endeavouring to get one of these measures made for myself, in 
which I need hardly say I have failed, I set to work to try if 
possible to do something for this branch of research ; the few 
remarks, therefore, which I now beg to offer I hope will meet with 
your full approbation. 
The class of instrument that I have employed throughout is an 
ordinary Sorby-Browning micro-spectroscope ; with respect to the 
measure, I have adopted a fitting somewhat like that used by 
Mr. Browning in his bright -spot micrometer, but with this 
VOL. XVI. X 
