On the Blood Corpuscles of the Mammiferous Animals, 1 95 
four long upright hooks, in which the lower end of the chimney 
rests ; or still better if the lamp be so originally constructed 
as to sustain the chimney at the required elevation without 
such addition, by thin laminae of brass or iron, having their 
planes directed to the axis of the wick. 
The proper elevation is best determined by trial ; and as 
the limits within which it is confined are very narrow, it would 
be best secured by a screw motion applied to the socket on 
which the laminae above mentioned are fixed, by which they 
and the chimney may be elevated or depressed at pleasure, 
without at the same time raising or lowering the wick. Ap- 
proximately it may be done in an instant, and the experiment is 
not a little striking and instructive. Take a common Argand 
lamp, and alternately raise and depress the chimney vertically 
from the level where it usually rests, to about as far above 
the wick, with a moderately quick but steady motion. It 
will be immediately perceived that a vast difference in the 
amount of light subsists in the different positions of the 
chimney, but that a very marked and sudden maximum oc- 
curs at or near the elevation designated in the commence- 
ment of this letter : so marked indeed as almost to have the 
effect of a flash if the motion be quick, or a sudden blaze 
as if the wick-screw had been raised a turn. The flame con- 
tracts somewhat in diameter, lengthens, ceases to give off* 
smoke, and attains a dazzling intensity. 
With this great increase of light there is certainly not a 
correspondingly increased consumption of oil. At least the 
servant who trims my lamp reports that a lamp so fitted con- 
sumes very little if any more oil than one exactly similar on 
the common plan. 
I have the honour to be, Sir, 
Your obedient servant, 
Slough, Feb. 15, 1840. J. F. W. Herschel. 
XXXVI. Observations on the Blood Corpuscles^ or RedPar- 
ticles, of the Mcmmiferous Animals. By George Gulliver, 
P.R.S.i F.Z.S., Assistayit Surgeon to the Royal Regiment of 
Horse Guards. No. III.^^ 
A N account is now to be given of the blood corpuscles of 
several other mammalia which I have examined since 
the publication of my last papers ; and similar communica- 
tions will be continued occasionall}^ until the observations 
have been made as complete as possible, when, as already in- 
timated, they will be presented in a systematic form, so as to 
* Communicated bv the Author. 
0'2 
