September 28, 191 1] 



NATURE 



4*5 



■ji, 



LETTERS TO THE EDITOR. 

 Editor docs not hold himself responsible for opinions 



expressed by his correspondents. Neither can he undertake 



to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part ../Nature. 

 No notice is taken of anonymous communications.] 



The "Earthquake House" at Comrie. 



I recently visited the " Earthquake House " at Connie, 



and was sorry to find that, in the matter of repairs, it had 



been neglected for a long time, and was in a very 



ted condition. 



It may be remembered that this small building was 



erected in 1872, through the combined efforts of the British 



Association and Mr. Drummond, for the purpose of carrying 



on observations on the, then, frequent manifestations of 



seismic activity experienced in that district, and I believe 



the investigations made there, with the simple apparatus 



and methods employed, represent some of the earlier 



attempts to obtain definite data respecting the direction, 



duration, and intensity of seismic vibrations. From these 



and other early observations, I suppose, the modern science 



of experimental seismology has been evolved, and for this 



the building should always be regarded as of great 



scientific and historical intcn -t, and its preservation a 



1- of common desire. Though the original wooden 



pins which were used have disappeared, some of the white 



sand that was placed on the floor some forty years ago is 



still to be seen there. 



Mr. J. J. Macdonald, of the Commercial Bank, Comrie, 

 lost kindly associated himself with me in an endeavour 

 to obtain permission to place this property in the hands of 

 a committee, and to raise funds for the purpose of pro- 

 g it and putting it in a proper state of repair. We 

 propose to fence it in so that it may lie preserved from tin- 

 depredations of children and others (who now have free 

 to it) for all time. 

 Without now entering into the details of the trouble and 

 correspondence our negotiations have entailed, I may say 

 that the owner has kindly given us full permission to take 

 such stens as may be necessary for the restoration and 

 'ion of the building, and that we hope to place it. as 

 far as possible, in its original condition without delay. 



An estimate has been submitted to us, and the sum 

 required to carry out all the necessary work is about 30/. 



Max I ask those of your readers who are interested in 



this matter to subscribe towards this sum? Mr. Macdonald 



has kindly consented to act as treasurer, and all donations 



Id be sent to him without delay. The names of those 



ng the committee, 1 list of subscribers, and the details 



work done, will 1" published later. 



Cecil Carus-Wtxson. 

 mi, September n. 



The Upper Trade-winds. 



Recently Herr Peppier l directed attention to the fart 

 that the air-pressure gradient from the equator towards 

 the subtropical zones, which is positive at the heights at 

 which the anti-trade-win. Is blow, must be negative in still 

 higher layers ( + 20 km.). 



Owing to the low temperature of the stratosphere abovi 

 the equator, the. mean temperature of the whole air-column 

 up to these heights is lower above the equator than 

 the subtropical zones, and Herr Peppier accordingly sup- 

 that the air pressure at the top of the column i 

 lower. 



Consequently, we may expect to meet above the anti- 

 trade a wind blowing towards the equator, and it would 

 be reasonable to call this wind the upper trade-wind (Ober- 

 bassat; Vent alizi supirieur). The ascents of registering 

 and pilot balloons made during the last two Years at 

 Batavia Observator; n some proof of tire exist- 



of this upper trade-wind. 

 Regarding the air-pressure gradient, I compared the 

 ures recorded during the balloon ascents made on the 

 Otario cruises in the North Atlantic, in +30° N. latitude, 

 with those found at Batavia in the corresponding southerly 

 1 Beitrage zur Phy-ik der freitn AtmosphSre. Bd. iv., Hefi 1. 

 NO. 2187. VOL. 8/] 



season. These mean pressures and differences follow here- 

 under : — 



Height 



164 



139 

 119 



IOO 

 86 

 74 

 63 



Though the records are few in number, the decrease and 

 reversal of the gradient are conspicuous. 



The numerous balloon-flight observations now made in 

 Batavia (the results of which are just going to the press) 

 have proved that the anti-trade reaches a maximum at a 

 height of 12—15 km. (if trie dry season lowest and in the 

 rainy season highest). Higher up its strength decreases, 

 and at heights of + 17 km. feeble southerly and westerly 

 winds blow. Berson was the first to observe these winds 

 in Central Africa. 



The height at which I found them above Batavia, viz. 

 + 17 km., corresponds exactly with that in which the 

 pressure gradient passes the zero value. 



Still higher up we must expect to meet the upper trade, 

 and the explanation of the occurrence of these southerly 

 and westerly winds simply is that they are feeble winds 

 of variable direction occurring between two great 1 

 lying air currents, similar to lie's. which are often 

 observed in the layers between trade and anti-trade, or 

 monsoon and trade. 



Recently the ascent of a balloon of 2 kg., 1 which 

 d -'2 km., gave fair evidence of the existence of the 

 upper trade, as may be seen from the wind directions and 

 given hereunder : — 



Wind Velocity 



H< 



Height 



bio 



The present dry season is not advantageous for the 

 discrimination of the upper trade from the upper easterly 

 counter-wind, because, according to the difference observed 

 between the dry and wet season, in this season pressure 

 at those heights is lowest probably over Java and not 

 uver the equator. Consequently, the southerly components 

 by which the upper trade differs from this counter-wind 

 will be small. 



In the rainy season (December-February), however, the 



contrary will be the case, and accordingly I expect to 



obtain in those months observations which will give 



stronger evidence of the existence of the upper trade-winds. 



W. van Bemmelen. 



Batavia Observatory, August 20. 



Rainfall in the Summer of 191 1. 



One floes not hear much of effort on the part of official 



1 logists to supply long-range forecasts of months, 



seasons, &c. It may be said, the thing cannot be done; 

 better to say, it cannot be done infallibly. My own experi- 



1. ..Is me to think a beginning might now- be made 



with what will no doubt some day be a familiar institu- 

 tion, like the useful but imperfect daily forecast. 



