NATURE 



17 



THURSDAY, FEBRUARY 22, 1872 



THE ROCK THERMOMETERS AT THE 

 ROYAL OBSERVATORY, EDINBURGH 



THE whole of the observations made with these 

 instruments (reading to hundredths of a degree 

 Fahrenheit) from 1837 to 1S69 having been reduced on a 

 uniform plan, and found to exhibit some well-marked 

 supra-annual cycles, a paper on the subject and on their 

 relations to the sun-spot cycles of similar period but 

 diverse shape was sent in to the Royal Society, London, 

 on March 2, 1S70. 



Since then two eminent astronomers, one of them being 

 Mr. Stone, the newly appointed Astronomer Royal at the 

 Cape of Good Hope, and the other Mr. Cleveland Abbe, 

 Director of the Cincinnati Observatory, have published 

 somewhat similar deductions touching atmospheric tem- 

 peratures in reference to sun-spots ; Mr. Stone basing on 

 thirty years of South African temperature observed by 

 his indefatigable predecessor Sir T. Maclear ; and Mr. 

 Abbe on sixty years' temperature observed on the elevated 

 station of Hohenpeissenberg near Munich, under the 

 superintendence of Dr. Lamont, the Bavarian Astronomer 

 Royal ; both parties, equally with myself, using the same 

 famous series of observations of sun-spots, as made by 

 M. Schwabe, and discussed both by Prof. Wolf and Prof. 

 Balfour Stewart. More recently still a Canadian writer, 

 employing the returns of the Toronto Observatory for 

 many years past, considers that he has established a con- 

 nection between the amount of annual rainfall there and 

 the sun-spots ; and of these again with the periods and 

 dates of several interlacing streams of circum-solar 

 meteors. And within the last few days the Radclifle 

 Astronomer announces in his report for 1871 that the 

 tiiea/i azimuthal direction of the wind at Oxford, rigorously 

 computed from automatic records during the last eight 

 years, varies year by year through a range of 58^ on the 

 whole, between niaximicm and minimum of visible sun- 

 spots ; the tendency of the wind to a westward direction 

 increasing with the number of spots, and with such west 

 wind, it is to be presumed, the amount of rain also. 



These results touch closely on the hopes of phjsicists 

 to render meteorology more of an exact science by getting 

 at its cosmical relations, but they also touch equally close 

 on another point where the highest science is at present 

 completely dumb, although too it is the very point where 

 the utmost amount of benefit might be conferred on the 

 largest numbers of the people, viz., some approximate in- 

 dications of the character of the seasons for a year or 

 two beforehand ; or indeed, very much as I did make a 

 first attempt, for the two winters of 1870-71 and 1871-72, 

 in the paper presented to the Royal Society in the spring 

 of 1870. 



How intimately the well-being of the poor generally, 

 as well as of the agricultural classes, depends on those 

 characteristics of weather which no scientific society can 

 at present .oretell, and no Ministry prevent in their 

 destructive effects to the national revenue when they do 

 come, the following letter may serve as a better example 

 than anything that I could prepare on theory alone : — 



"Webb's Green, Hales Owen, June 12, 1871 

 " To C. Piazzi Smyth, Esq., Edinburgh 

 (Copy) 



" Sir, — I am a reader of Chamber^ Journal and a 

 farmer of some 600 acres. In the publication of Messrs. 

 ChambeiS I read that you had expressed an opinion from 

 certain observations you had made that the late winter 

 would be very severe. For the general run of weather 

 prophets I have very little respect ; but every respect for 

 opinions that are the result of scientific induction. 



" Consequently I conducted my farming operations with 

 due regard to your prognostication, and as the result has 

 been a profit to me, I write to thank you. Gratitude has 

 been defined as ' a lively sense of favours to come,' and 

 from that view and in consideration of the present 

 weather if you could give me your opinion of the weather 

 that you think likely to prevail for some time to come I 

 should feel much obliged. 



" I have not troubled you with this epistle entirely 

 from a selfish point of view, for besides being a farmer I 

 am unfortunately an employer of a very underpaid class 

 of workmen, hand rail makers. 



" Now that stocks of wheat are exhausted, meat is a 

 luxury to which railers cannot aspire ; and if the season 

 continues ungenial, before the harvest of 1872 there may 

 be absolute scarcity of bread. I want to get up a fund 

 for emigration, but if you could give me any information 

 as to the probabilities of season that would dispel my 

 gloomy anticipations for next winter, I should rejoice. — [ 

 am, &c., &c. (Signed) "Thomas Eissell" 



But I have so little desire to incur responsibiUty for any 

 weather predictions that I have gladly availed myself of 

 the opporUmity of the publication of the 13th volume of 

 the Edinburgh Astronomical Observations to lay before 

 the public by means of the several Plates 11 to 15 inclu- 

 sive a complete graphical representation of the whole 

 series of Edinburgh rock-thermometer observations, and 

 on which I will merely venture the following explanatory 

 remarks : — 



1. The most striking and positive feature of the whole 

 series of observations is the great heat-wave which occurs 

 every eleven years and a fraction, and nearly coincidently 

 with the beginning of the increase of each sun-spot cycle 

 of the same eleven- year duration. The last observed 

 occurrences of such heat-wave, which is very short lived 

 and of a totally different shape from the sun-spot curve, 

 were in 1834-8, 18464, 1857-8, and i!i68-S, whence, allow- 

 ing for the greater uncertainty in the earlier observation 

 we may expect thu next occurrence of the phenomenon 

 in or about iSSo-o. 



2. The next largest feature is the extreme cold close on 

 either side of the great heat-wave ; this phenomenon is 

 not quite so certain as the heat-wave, partly on account 

 of the excessive depth and duration of the particular cold 

 wave which followed the hot season of 1834-8. That ex- 

 ceedingly cold period, lasting as it did through the several 

 successive years 1836, 37, and 38, was, however, appa- 

 rently a rare consecjuence of an eleven year minimum 

 occurring simultaneously with the minimum of a much 

 longer cycle of some forty or more years, and which has 

 not returned within itself since our observations began. 

 Depending therefore chiefly on our later observed eleven- 

 year periods, or from 1S46-4 to i857'8, and from the 

 latter up to i868'8, we may perhaps be justified in con- 

 cluding that the minimum temperature of the present 

 cold wave was reached in 1871-1, and that the next similar 

 cold wave will occur in 1878-8. 



