686 
British Association . 
[October, 
falling upon the compound of carbon and rendering it visible, 
in the same way that light renders the moon, the planets, 
and other opaque objedts visible, the vapour of carbon being 
opaque in reference to the particular rays, which appear as 
bright lines in its spedtrum. 
Dr. Janssen, Member of the Institute of France, and 
Director of the Observatory, Meudon, read a paper “ On 
Photographic Specdtra of Short Exposure,” in which he 
showed that in the solar spedtrum the point of maximum 
adtinic intensity was near the line G, while the point of 
maximum luminous intensity was near D. It occupied 
sensibly the same position for nearly all photographic 
substances and for lenses of different material. The time 
of exposure was graduated from five minutes to a small 
fraction of a second. By this means results were obtained 
which pradtically afforded a chronometric method of analysis 
of the solar spedtrum. They had a bearing on the question 
of oxygen in the sun, and they led to pradtical improvements 
in the construction of photographic apparatus. 
Mr. H. Courtenay Fox read a paper “ On the Synchronism 
of the Mean Temperature and Rainfall in the Climate of 
London. The paper was accompanied by copious tables 
exhibiting the months and seasons for sixty-seven years, 
arranged in the order of their respective temperature and 
rainfall as for the Royal Observatory. The following is a 
short summary of the results : — i. In each of the four 
months from November to February, extreme cold tends to 
be synchronous with dryness, warmth with large rainfall. 
2. In the summer months, June to August, cold tends to be 
accompanied by much rain, warmth by dryness. 3. To put 
this in popular language, rain brings warmth in winter and 
cold in summer ; that is (if rain be the cause, which is by 
no means proven) it mitigates the special character of each 
extreme season, winter and summer. 4. Very wet years 
tend to be either cold or warm, whilst years of drought tend 
to assume an average temperature. 
A paper “ On Lightning Protestors for Telegraphic Ap- 
paratus ” was read by Mr. W. H. Preece. For many years 
it was not the practice in England to protecft telegraphic 
apparatus from the injurious effedts of atmospheric eledtricity 
because the damage done was so insignificant, and because 
the remedy was found to be worse than the disease. But 
as telegraph systems increased lightning protedtors became 
essential. Many forms were tried based on the fadt that 
when a discharge takes place through a non-condudtor, such 
