1868.] On Phijsical Observations to be undertaken in India. 287 



to Colonel Walker to be placed in the hands of observers at different 

 stations. 



" The observation of the polarization would also require the use of a 

 telescope, which, however, may be of much smaller size, such as 2 inches 

 aperture, and will therefore be comparatively inexpensive. 



" The Committee estimate that the whole cost of the instruments they 

 have recommended, for the use both of Mr, Hennessey and of those gentle- 

 men who may undertake the observations of the eclipse, will be under ^300." 



This Report was presented to the Council on the 20th of June, 1867. 

 The Council adopted the report and requested the Committee to take the 

 requisite steps for carrying out their recommendations. They further re- 

 solved that application be made to the Government-grant Committee for 

 a sum of not exceeding ^300 to defray the expenses, and that the Trea- 

 surer be authorized to make such advances within that sum as might in the 

 meantime be required to enable the Committee to proceed with the work. 



Mr. Huggins kindly undertook to superintend the construction of the 

 instruments, and to give instruction in the use of the star-spectroscope to 

 the observer who might be selected to observe the spectrum of the red pro- 

 tuberances ; and it is mainly owing to Mr. Huggins' s zeal in the cause that 

 the instruments have all been got ready within the limited time allowed. 



The following instructions were drawn up for the guidance of the ob- 

 servers who might be entrusted with the observations which it was intended 

 to make on the occasion of the total solar eclipse : — 



Instructions respecting certain observations to be made in India on 

 the occasion of the Total Solar Eclipse of 1868^ by means of 

 Instruments sent out by the Royal Society. 



" ^ I. Special Objects of the Observations proposed to be made. 



According to modern opinion, the photosphere of the sun consists of a 

 shell of liquid or solid particles, constantly forming by condensation in the 

 outer layers of the intensely heated gaseous matter of the sun. When 

 nearly the whole of the light from the solar photosphere is screened off by 

 the moon during a total solar eclipse, two other, feebler sources of light 

 without the sun's photosphere usually show themselves. One of these is 

 in the form of an irregularly bright halo surrounding the sun, and is known 

 as the Corona. The other source of hght usually presents itself as small 

 tongue-shaped flames more or less coloured, which apparently issue forth 

 from the solar photosphere. 



"The special object of the observations suggested is to determine, as 

 far as may be possible, the physical nature of the ^ Corona ' and of the 

 ' Hed flames.^ 



" To obtain this information it is proposed to analyze the light from 

 these sources for polarization, and especially to observe its prismatic spec- 

 trum in both cases. 



2 D 2 



