The President's Address. 
55 
The spectroscope first employed in this way was that 
with which Mr. Huggins made his remarkable discoveries 
in the new science of Celestial Chemistry. Such an appa- 
ratus, however, was far from convenient, and Mr. Browning 
turned his attention to the subject with his accustomed skill, 
and soon produced the " Sorby-Browning Spectroscope,^^ 
which we have already described as in the highest degree 
effective and convenient. 
Mr. Sorby succeeded, at an early period of these inquiries, 
in obtaining characteristic spectra with exceedingly small 
quantities of blood : but with Mr. Browning^s apparatus, and 
with the use of Messrs. Smith and Becky's -aV^h, or Messrs. 
Powell and Lealand^s lisih, a distinct spectrum can be easily 
obtained from the third or the fourth of a single human 
blood-corpuscle. 
The size of such a corpuscle will vary, according to Mr. 
Gulliver, from . o "^h. to 3^J-^th : thus, if we take Twrot^ 
of a square inch of a human blood-corpuscle, we find that it 
contains enough of that peculiar substance cruorine to give 
a characteristic result. For such delicate experiments the 
blood must be quite fresh, and a red-coloured corpuscle 
selected. 
In the ' Proceedings of the Boyal Society,^ July 19th, 1865, 
and in the July number of the ^ Popular Science Review,^ Dr. 
Beale published a paper on the " Highest Magnifying Powers, 
and their uses.^' In this paper Dr. Beale speaks of the diffi- 
culty of using the ^Vth and other high powers complained of by 
practical men, and points out very clearly that success in their 
use is dependent upon training. Dr. Beale says, It is neces- 
sary to begin by studying the simplest things in the easiest and 
simplest manner, and proceed only by degrees to the more 
complex.^^ This is the only process by which observers can 
hope for success; and it is this patient labour proceeding 
step by step, from the lowest to the highest, that constitutes, 
in fact, the diff'erence between a trained and an untrained 
observer, not only in Microscopy, but in all minute and accu- 
rate investigations. In the ordinary occupations of an obser- 
vatory the trained eye can see distinctly, and the educated 
hand measure accurately, that which the uneducated eye can- 
not see at all. So, doubtless, it is with the use of high powers 
as applied to the microscope : many beautiful details can be 
seen by the carefully-trained eye, and traced by the trained 
hand, of which not a trace is even suspected by observers 
wanting in this educated eye and equally important educated 
hand. 
In the September number of ^ Silliman^s Journal,^ Professor 
