266 



N/l TURE 



\ya!i 23. rS79 



A glance through the pamphlet will give an idea of 

 what kind of products different parts of the world are yet 

 capable of supplying. 



LETTERS TO THE EDITOR 



[ TJie Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspond with tlu wHters of, rejected manuscHpts. No 

 notice is taken of anonymous communications. 



[ The Editor urgently requests correspondents to keep their letteis as 

 short as possible. 7he pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com- 

 munications containing interesting and novel facts.\ 



American Weather 



I INCLOSE you a cutting from the Manitoba Weekly Free Press 

 of December 14, 1878, containing a record of what I cannot but 

 think is a phenomenon unsurpassed in the annals of meteoro- 

 logy. For a mouth to exceed its average temperature by the 

 amount of twenty-five degrees is scarcely credible even in such a 

 continental climate as that of Manitoba. An editorial para- 

 graph from the same paper which I also inclose will show that 

 the fact has not been overlooked by the Manitobans, and that 

 their attention has also been drawn to the occurrence of the 

 reverse characteristics in the weather over here. Surely . the 

 moral of all this is universal synoptic weather charts. The 

 whole thing at present is worked on far too small a scale. The 

 daily papers contain a weather chart which comprises scarcely a 

 quarter of Europe, and of what goes on outside the limits of this 

 we are practically ignorant, unless we hunt up reports when the 

 atmospheric conditions they refer to are long past. Even 

 granting the impossibility of drawing the daily isobars over the 

 North Atlantic, except hypothetically, would it not probably 

 have thrown much light on the proximate causes of, and probable 

 duration of, our recent cold weather here, had we been able to 

 secure a daily synoptic chart of the isobars over America, as 

 well as those over our own islands and the countries immediately 

 adjacent ? Surely the valuable results which would follow such 

 an extension of our present system would quite compensate for 

 the extra outlay incurred. E. D. Archibald 



January il 



" Weather Record for November 



*' The following is Mr. Stewart's monthly" record of the 

 weather : — 



"The highest reading of the barometer in the month was 

 29*650 at 7 A.M. on the 7th ; the lowest reading was 28*643 o" 

 the 26th, showing a monthly range of i *oo7 inches. The mean 

 barometrical pressure for the month was 29*1377 inches. The 

 highest temperature in the month was 53 "3 on the 1 7th ; the 

 lowest temperature was 10*3 on the 30th ; the warmest day was 

 the 17th, the mean temperature being 44*10; the coldest day 

 was the 29th, the mean temperature being 18*25. The 

 mean temperature of the month was 30*75, being 25*73 

 higher than the average of the month for the past seven years. 

 The mean monthly pressure of aqueous vapour, was 0*148, 

 and the mean humidity of the month was 83. The mean 

 amount of sky clouded was 0*45. The highest wind in the 

 month occurred at 8 A.M., on the 14th, the force being at the 

 rate of 24 miles per hour. The most windy day in the month 

 was the 14th, the average daily force being 15*92 miles per 

 hour ; the least windy day was the 7th, the average daily force 

 being 2*42 miles per hour ; the mean monthly velocity was 7*89 

 miles per hour. The prevailing direction of the wind was south. 

 The total amount of rain that fell during the month was 0*070 

 inches ; total amount of snow, i "45. Total precipitation of 

 rain and melted snow, 0*220 inches. The Red River opened 

 again on the i8th. On the same day the steamboat Lady Ellen 

 arrived from Lake Winnipeg ; on the 23rd the steamer Cheyenne 

 arrived from Pembina. The Red River was finally frozen over 

 on the 27th. Two auroras and two lunar coronas were seen in 

 the month." 



The following is the editorial comment referred to : — 

 " The peculiar freaks of the weather during the last year or 

 wo have defied the most ingenious efforts of the weather 

 prophets to foreshadow its complexion with any degree of truth- 

 fulness. It is a comparatively easy task to depict the general 

 characteristics of a season under ordinary circumstances, when 



the seasons for a number of years have shown no marked devia- 

 tion from their usual regularity, but the abnormal nature of the 

 w eather of late has set the prophets completely at sea. The 

 predictions of those wiseacres who, a month or two ago, told 

 us the present season was to be excessively severe, and cited the 

 musk-rats, the beavers, and the cornshucks, to support the prog- 

 nosis, have not been verified up to the present, and without 

 attempting the prophecy business ourselves, we would remark 

 that the indications are against any unusual severity this season. • 

 Noveinber has been mild to a marked degree, and indeed the whole 

 fall, which has just passed into winter, has been exceptionally 

 pleasant. There has been severe weather both in Europe and 

 Asia, and heavy frosts have fallen \ in England, Austria and 

 Italy — and it has been remarked that when the winters in the 

 Old World are very cold, they are very moderate in America." 



The Microphone 



In a recent letter (Nature, vol. xix. p. 221) Dr. Bleekrode 

 mentions the fact that a microphone through which a strong 

 current is sent emits an audible sound ; the electro-dynamical 

 action of the current on its movable part is considered the 

 origin of it. 



The experiment is a very interesting one, and is nearly related 

 to the facts I published in Nature, vol. xviii. p. 642. But \ 

 cannot aT;ree with Dr. Bleekrode in the interpretation. It is 

 my opinion that no electro-dynamical action is in play, but 

 only a dilatation at the points of contact. 



In a circuit were placed a battery, a tangent-galvanometer, 

 and two pieces of carbon, which supported a third one. A 

 sound was heard and sparks were seen. The galvanometer 

 showed that the intensity of the cuiTcnt increa?ed, the deflec- 

 tion increasing from five to ten degrees. This proves the in- 

 fluence cf the clouds formed at the points of contact. 



The pieces of carbon were then inclosed in very flat sheets 

 of platinum, and the experiment repeated. No sound was 

 heard ; the deflection of the galvanometer rose to 28°. When 

 a rough sheet of platinum was taken the inten:-ity of the 

 current fell again, sparks were seen, and a sound was heard. 



Dr. Bleekrode believes that, the coefficient of dilatation of 

 carbon being small, the sound cannot be caused by dilatation at 

 the points of contact. But the temperature of those points is 

 very high, a great part of the heat generated in the circuit being 

 produced here. 



I cannot see that his experiment is a true demonstration of 

 the repulsive action between the subsequent parts of a current. 

 In my opinion the experiments of von Ettingshausen {Sitzungs- 

 ba-ichtc der Wiener Akademie, Ixxvii. p. 109) are considerably 

 more convincing. Von Ettingshausen found that, with a cur- 

 rent which was iomewhat stronger than the one I made use of, 

 the influence of the earth-magnetism was almost as great as that 

 of the electro-dynamical action. Moreover, this action depends 

 upon the relative position of the movable part and the ether 

 parts of the circuit. Now I have not been able to detect the 

 slightest variations in the sound by changing the position of the 

 movable piece of carbon in relation to the direction of the dip- 

 ping needle, or in relation to the other parts of the circuit. 



I therefore hold to the explanation of the acting of the micro- 

 phone as a receiver, which I believe I was the first to propose. 

 In my opinion it depends upon the varying dilatation at the 

 points of contact by the varying intensity of the current. 



Breda, Holland, January 13 V, A, Julius 



The Formation of Mountains 

 The quotation given by Mr, Wallace from the English 

 Cyclopedia affords a sufficient basis to prove "the more rapid 

 [present] cooling of the interior of the globe than of the cru^t. 

 I will add a passage from Sir W. Thomson's "Secular Cooling 

 of the Earth," of a like tendency : " I think it cannot be denied 

 that a large mass of melted rock, exposed freely to our air and 

 sky, will, after it once becomes crusted over, present m a few 

 hours or a few days, or at most a few weeks, a surface so cool 

 that it can be walked over with impunity. Hence, after 10,000 

 years, or, indeed, I may say a single year, its condition will be 

 sensibly the same as if the actual lowering of temperature expe- 

 rienced by the surface had been produced in an instant, and 

 maintained constant ever after." ^ 



' Trans. R.S. Edin., 1862; also Thomson and Tail's "Nat. Phil.," 

 App. D. 



