1878.] 



107 



1 Barker. 



this occasion we have ascertained the true nature of the corona, viz: it 

 shines by light reflected from the sun by a cloud of meteors surrounding 

 that luminary, and that on former occasions it has been infiltrated with 

 materials thrown up from the chromosphere, notably with the 1474 matter 

 and hydrogen. As the chromosphere is now quiescent this infiltration has 

 taken place to a scarcely perceptible degree recently. This explanation of 

 the nature of the corona reconciles itself so well with many facts that have 

 been difficult to explain, such as the low pressure at the surface of the sun, 

 that it gains thereby additional strength." 



Tasimetric Observations. 



As this eclipse is the first in which any attempt has been made to measure 

 the heat of the solar corona, Dr. Edison's report to Dr. Draper on this sub- 

 ject is here quoted in full. He says : 



"The instrument which I used at Rawlins, Wyoming, during the solar 

 eclipse of July 29th, 1878, for the purpose of measuring the heat of the 

 sun's corona, was devised by me a short time only before that event, and 

 the time was insufficient to give it as thorough a test as was desirable to 

 ascertain its full capabilities and characteristics. 



"This instrument I have named the tasimeter, from the Greek words, 

 raffig, extension, and fierpov, measure, because primarily the effect is to 

 measure extension of any kind. The form of instrument which I used is 

 shown in the annexed wood cut (Fig. 2.) 



Fisr. 2. 



"With this instrument was used a Thomson's reflecting galvanometer 

 on a tripod, having a resistance of three-fourths of an ohm. The galvanom- 

 eter was placed in the bridge wire of a Wheatstone balance, two of the 

 branches of which had constant resistances of ten ohms each, while of the 



