Feb. 25, 1875] 



NATURE 



329 



helion passage occurred on the same day of April, Encke 

 was very doubtful of the comet being visible at all in this 

 hemisphere, and had contented himself with transmitting 

 an ephemeris to Greenwich, to be passed on to the Cape 

 of Good Hope. It was only after Dr. Galle had detected 

 with the Berlin refractor, on the evening of February S, 

 a very faint nebulosity within 2' of the predicted position 

 of the comet, that Encke communicated the ephemeris 

 to the Astroiwmische Nacltrichtcit (see No. 443). In 

 1842, on March 23, the comet was seen " distinctly in the 

 twilight, with the moon shining brightly." At the begin- 

 ning of the second week in April the condensation of 

 light was very great, and a fine bright point was re- 

 marked : it was not seen in Europe after the 9th of this 

 month. 



BEARING OF METEOROLOGICAL RECORDS 

 ON A SUPPOSED CHANGE OF CLIMATE 

 IN SCOTLAND* 



IT is a belief very generally entertained that the climate 

 of Scotland has undergone considerable change in 

 recent years, the summers being less hot and the winters 

 less severe than they used to be. This idea was advocated 

 by Mr. INI'Nab in his presidential address to the Edin- 

 burgh Botanical Society in November 1873, the facts 

 adduced in support of it referring solely to vegeta- 

 tion. In this paper the question is examined e.xclusively 

 from a meteorological point of view, and the examina- 

 tion is confined to monthly mean temperatures. 



The following are the records which have been made 

 use of: — I. Monthly mean temperatures from observa- 

 tions made at Gordon Castle, Banffshire, from July 17S1 

 to November 1S27 ; 2. The monthly temperatures given 

 in Forbes' climate of Edinburgh (Trans. Roy. Soc. Edin., 

 vol. xxii. p. 335) ; 3. Observations made at Dollar from 

 1S36 to 1856, and from 1861 to 1874 ; and 4. Observations 

 made at Elgin from 1855 to 1874. The mean tem- 

 peratures of the months and the year were calculated for 

 each of these four series of observations for the interval 

 embraced by each, and then the differences of each 

 month's mean temperature from the general mean for 

 that month and station were set down in a table. Since 

 the time over which each of these series of observations 

 extended was sufficiently long to give a very close 

 approximation to the true mean for the hour of observa- 

 tion and exposure of the thermometers, and since the 

 separate months were only compared with the means for 

 that place, the table may be regarded as representing 

 very closely the iiwiilh/y van'atioiis which have occurred 

 in the temperature of Scotland during the past ninety-four 

 years. It may be noted that the observations were made 

 in two districts, viz., Gordon Castle and Elgin in the 

 north, and Edinburgh, Dunfermline, and Dollar in the 

 south. 



The variations of each year, and of each month of 

 each year, were then projected in curves, showing graphi- 

 cally the fluctuations which have occurred during this 

 long period. The coldest year was 1782, being 3°-3 

 under the average, the deficiency of May of that year 

 being 6°'y, and August 5^9 ; then follow 1799 and 18 16, 

 being 2°'3; 1S38, being 2"'o; and 1S60, being 2°'4 under the 

 average. The two warmest years were 1 794 and i S46, 

 the excess being respectively 2"'7 and 2'g. During the 

 nine years from 1787 to 1795, the temperature was gene- 

 rally above the average ; the mean annual excess of the 

 nine years being i'"5. For the next quarter of a century 

 temperatures were generally under the average. From 

 this period to the present time there have occurred five 

 fluctuations in the annual temperature above and below 

 the average, differing in ampHtude and duration, but 

 giving no indication of a steady permanent change either 

 way. Exceptionally warm and exceptionally cold months 

 leneral Meeting of the Scottish Mtteo- 



are distributed over the period in such a manner as to 

 show that substantially no permanent change has taken 

 place in the temperature of any of the months. 



Since, however, the eye may not be able easily to detect 

 any steady rise or fall that may be going on owing to 

 the sharply serrated character of the curves, other 

 averages were calculated on the method of taking as the 

 average of, say, January 17S4, not the average of that 

 year, but the average of the five years 1782, 17S3, 17S4, 

 i7H5,and 1786. All the averages were dealt with in this way^ 

 and the results projected in a set of thirteen new curves. 

 From these consecutive five years' averages, it is seen 

 that mild Decembers prevailed from 17S7 to 1797, 

 from 1822 to 1845, and from 1862 to 1867 ; and cold 

 Decembers from 1798 to 1821, from 1846 to iS6r, and 

 from 1 868 to the present time. It may be noted that in 

 1821 the remark might have been made from the previous 

 forty years' observations, that the character of Christmas 

 weather had undergone a great change, the Christmases 

 of the latter part of the period being generally much more 

 severe; and again, in 1843, looking at the long period of 

 forty-seven years, beginning with 1796, it might have been 

 said that the old-fashioned Christmas weather had almost 

 ceased to occur in the latter half of this long period, and 

 that the climate had undergone some great permanent 

 change. Now, while both would have been right as to 

 the facts (whether these facts were based on numerical data 

 or on recollections), both would have been wrong in in- 

 ferring a permanent change, even though the inference was 

 based on the observations of half a century. Looking, 

 however, at the ninety-four-years' period, we can only con- 

 clude that the weather of December, as regards tempera- 

 ture, is subject to large fluctuations, which differ both in 

 intensity and duration, and that there is no tendency to a 

 permanent increase or decrease. 



One of the most interesting features of the curves is 

 the similarity existing among them ///Ay st'. The curves 

 for August and September closely resemble each other, as 

 also do those for November and December, while that for 

 October combines the main features of the two sets. The, 

 curve for January combines the main features of the 

 curves for November and December on the one hand 

 and February and March on the other, and so on with 

 the other months. 



The general result of the inquiry then is, that though 

 large annual fluctuations of temperature have occurred, 

 yet the warm and the cold cycles, extending over longer 

 or shorter periods, are so distrijjuted over these long 

 intervals as to give no indication that there has been any 

 tendency towards a steady increase or decrease in the 

 temperature, or that any permanent change has taken 

 place in the climate of Scotland. And since the same 

 remark applies with equal force to the observations of the 

 separate months, it follows that meteorological records give 

 no countenance to the idea of a permanent change having 

 occurred in the climate of Scotland either as regards 

 summer heat or winter cold. It may be added that 

 during the past seven years the temperature of July has 

 been above its average respectively 2°'8, i°7, 2°'o, o''2, 

 i'7, i°'o, and i°'8, and that of December, as compared 

 with its average -\- i°'5, - 4°'2, - 5-6, - i"'!, - o'-8, -\- 

 3 '4, and — 7°"4 ; results quite in the opposite direction of 

 the popularly entertained belief that the summers are 

 colder and the winters milder than formerly. 



Alexander Buchan 



NATURAL PHENOMENA IN SOUTH 



AMERICA * 



'T'HE following notes may, I hope, possess some 



■*■ interest for the readers of Nature. They were 



made during an expedition which took place last 



* Notes of some observations made by a telegraphist during a cable- 

 laying expedition from Para to Cayenne. 



