314 
NATURE 
{F2s. 20, 1873 
will make its working more perfect, images of the chromo- 
sphere, almost in its entirety, have already been seen on several 
days during the present month and the latter part of last 
month. 
The adaptation of this 
seen at a glance from the accompanying drawing. 
The image of the sun is brought to focus on a diaphragm 
having a circular disc of brass (in the centre) of the same size as 
the sun’s image, so that the sun’s light is obstructed and the 
Fig. 1.—Diaphr 
looking thro: 
inside B, and 
spectroscope. 
h apertures in the side of the tubes.—Fig. 2. 
G. Collimator of spectroscope. 
methed to a telespectroscope will be | 
diverzent to pass through the prisms at the same time, and that | 
the image of the whole annulus may be seen at once. There are 
mechanical difficulties in producing a perfect annulus of the re- 
quired size, so one } inch in diameter is used, and-can be reduced 
virtually to any size at pleasure. 
The proposed photographic arrangements are as follows : 
A large Steinheil spectroscope is used, its usual slit being re- 
placed by the ring one. 
December 6, 187 
2, at 11.30. ae 
Outer circle roo sec, from inner one. 
The size of the image of the chromosphere obtained by the 
method adopted will be seen from the accompanying photograph, 
taken when the ring-slit was illuminated with the vapours of 
copper and cadmium. 
As this photograph is not reproduced, it may be stated that 
the ring-images have an internal diameter of nearly } of an 
inch. 
The accompanying solar profiles are copies of drawing made, 
on the dates stated, by means of the new method, which were 
exhibited by the authors at the meeting. 
[Since reading the above paper it has come to our knowledge 
that Zollner had conceived the same idea unknown to us, but 
had rejected it. Prof. Wenlock in America has tried a similar 
arrangement, but without success.—J.N.L., G.M.S., January 
17, 1873.] 
Feb. 13.—‘* Ona new Relation between Heat and Electricity,” 
by Frederick Guthrie. 
It is found that the reaction between an electrified body and a 
neighbouring neutral one, whereby the eletricity in the neutral 
body is inductively decomposed and attraction produced, under- 
goes : modification when the neutral body is considerably 
heated. 
Under many circumstances it is found that the electrified 
chromospheric light is allowed to pass, The chromosphere is 
| afterwards brought to a focus again at the position usually oc- 
| cupied by the slit of the spectroscope ; and in the eye-piece is 
‘ seen the chromosphere in circles corresponding to the “C” or 
other lines. The lens D is used to reduce the size of the sun’s 
image, and keep it of the same size as the diaphragm at different 
times of the year ; and the lenses F areused in order to reduce 
the size of the annulus of light to about } inch, so that the 
pencils of light from either side of the annulus may not be too 
Fic. 2, 
howing annulus, the breadth of which may be varied to suit the state of the air. The annulus is viewed and brought to focus by 
: A. Sliding eye-tube of telescope. 
arrying lens D and diaphragm E. F. Lenses bringing image of diaphragm to a focus at the place generally eccupied by the slit 
C. Tube sliding 
of the 
B. Tube screwing into eye-tube. 
A solar beam is thrown along the axis of the collimator by a 
heliostat, and the sun’s image is brought to focus on the ring-slit 
by a 33-inch object-glass, the solar image being made to fit the 
slit by a suitable lens. 
By this method the image of the chromosphere received on 
the photographic plate can be obtained of a convenient size, as a 
telescope of any dimensions may be used for focussing the 
parallel beam which passes through the prisms on to the plate, 
December 7, 1872, at 11.30. 
Chromosphere at normal height, except where prominences marked 
body is rapidly and completely discharged. The action of dis- 
charge is shown to depend mainly upon the following condi- 
tions :—(1) The temperature of the discharging body and its 
distance from the electrified one. (2) The nature (+ or—) of 
the latter’s electricity. 
With regard to (1), it is shown that the discharging power of 
a hot body diminishes with its distance and increases with its 
temperature. But, concerning the temperature, it is proved that 
| the discharging power of a hot body does not depend upon the 
quantity of heat radiated from it to the electrified body, but 
chiefly upon its quality. Thus a white hot platinum wire con- 
nected with the earth may exercise an indefinitely greater dis- 
charging power, at the same distance, than a large mass of iron 
at 100° C., though the latter may impart more heat to the elec- 
trified body. 
Neither the mere reception of heat, however intense, by the 
| electrified body, unless the latter have such small capacity as to 
be itself intensely heated, discharges the electricity if the source 
of heat be distant : nor is discharge effected when the electrified 
body and a neighbouring cold one are surrounded by air through 
which intense heat is passing. But, for the discharge, it is 
necessary that heat of intensity pass to the electrified body from 
a neutral body, within inductive range. 
