THE ECLIPSE OF 1878. 139 



Edison, who has recently added to his feat of crystal- 

 lising sound (to speak fancifully) the seemingly not 

 less impossible achievement of * talking a hole through 

 a deal board' (to speak strictly by the letter), has 

 devised a most ingenious instrument, which he calls 

 the tasimeter (or strain-measurer), for estimating small 

 changes of temperature. This instrument was em- 

 ployed during the recent eclipse to compare the heat 

 received from parts of the sky remote from the eclipsed 

 suh with that received from the corona. It gave the 

 clearest possible evidence of the fact that heat comes 

 to us as well as light from this vast solar appendage. 



The last discovery to be noticed (as bearing at 

 least on questions of solar physics) is in some respects 

 even more important than any we have yet considered. 

 Every student of astronomy knows that after sunset 

 in spring, and before sunrise in autumn, a faint illu- 

 mination of the sky can be seen above that part of the 

 horizon beneath which the sun lies. It has long been 

 recognised that the lens-shaped light thus seen, called 

 the zodiacal light, indicates the presence of matter 

 surrounding the sun, to a distance exceeding probably 

 that of Mars, and certainly that of Venus, from the sun. 

 It had been suggested that the inner and brighter 

 portion of this solar appendage might be recognised 

 during total eclipse by an observer who should devote 

 himself specially to the task. In the monthly notices 

 of the Astronomical Society for 1869-70, page 149, the 

 present writer, in a paper on ' The Solar Corona and the 

 Zodiacal Light,' pointed out the value of observations 



