HISTORY OF THE 
164 
[1860-70 
the Cape, and Williamstown, Victoria, resulted in a value of the 
solar parallax 8"-94 {Mem. R.A.S., 33 , 77). Similar reductions made 
by Winnecke, of observations made in 1862 at Pulkova and the 
Cape, resulted in a parallax of 8 "-96. From a rediscussion of the 
observations of the Transit of Venus 1769, Stone, by a reasonable 
interpretation of some of the descriptions given by observers, 
deduced a solar parallax 8"-9i ( M.N ., 28 , 255). 
Thus it came about that Le Verrier’s value of 8 "-95 was intro 
duced in the Nautical Almanac for 1870, and continued in use until 
the Almanac for 1882, when Newcomb’s value 8"-85 was adopted. 
Great preparations were made in 1868 for observing the total 
eclipse of the sun on August 17-18. Two expeditions were sent 
out from this country to India, one under Major J. T. Tennant, 
arranged by our Society, with the financial aid of the Indian and 
Imperial Governments : and the other under Lieut. John Herschel, 
R.E., arranged by the Royal Society, with financial aid from the 
Parliamentary grant annually placed at the disposal of that 
Society. 
This eclipse is made memorable by the success of the observa 
tions which enabled both Tennant and Herschel to announce 
that the solar prominences exhibited bright lines in their spectra, 
indicating at any rate the presence of incandescent hydrogen and 
probably sodium and magnesium. Janssen’s observations during 
the eclipse convinced him that he would be able to see the 
prominences with the help of his spectroscope in full sunlight, 
and he recounted how for two or three days after the eclipse he 
had been living in a veritable fairyland of new observations. 
Lockyer, working in London, with apparatus which had long before 
been designed for this particular research, but of which the com 
pletion had been delayed for several months in a busy optician’s 
workshop, was able to make announcement of the success of his 
observations. It arrived at the Paris Academy only a few minutes 
before Janssen’s report from India, and the two investigators share 
the honour of the discovery of the new method. 
Another result of this eclipse was to bring about joint action 
between the Royal Society and our Society in making arrange 
ments for the observations of the eclipse in 1870 December. This 
joint action was renewed from time to time, until in 1892 it ceased 
to be temporary by the appointment of a Joint Permanent Eclipse 
Committee of the two Societies. 
In reviewing the impressions gained in reading through the 
records available for this chapter in the history of the Society, 
one is led to feel that it was a decade of great and wholesome 
activity. The heritage of large problems from the previous decade