September 6, 1 894] 



NATURE 



455 



good instruments, and has from time to time issued useful 

 bulletins. An interesting report upon the atmosphere of Paris 

 is published in the supfilement of La Nature of Au^st 25, 

 based on the observations made between July I, 1891, and 

 December 31, 1893, which shows very clearly the influence 

 exerted on meteorological elements by a large mass of houses. 

 M. Jaubert had compared the observations at his own obser- 

 vatory with those at the official observatory at Pare Saint-Maur, 

 in the suburbs of Paris. The tables show that the variations 

 of pressure between the two places are very small, but that 

 temperature, especially towards the evening, is from 3' to 4° F. 

 higher in the city, while the maxima and minima occur some 

 hour or two later than in the country. The amount of cloud 

 has this peculiarity, that during the evening the sky is clearer 

 over Paris than in the suburbs. All other elements, rainfall, 

 wind, &c., have been compared, and some interesting details as 

 to visibility are also given. We published some time since 

 (vol. xlix. p. 460) a similar comparison with reference to the 

 temperature of Berlin. Such statistics are of great practical 

 value, especially to persons living near large towns. 



Among some of the old German legends concrning the 

 weather, the recent meteorological conditions experienced in 

 Gottingen and its neighbourhood have turned nearly everyone's 

 mind to that very old one called the "seven sleepers," or 

 "Die Siebenschlafer " That such a belief should still be held 

 to these old legends is not to be wondered at, even in these 

 days of forecasts, &c. , for were they not to a great extent 

 founded on real, although roughly observed, facts which 

 had been noticed over the space of many years, and at 

 last become legendised ? The legend of the Siebenschlafer 

 runs as follows: — Seven Christian youths, Maximianus, 

 Malchus, Sirapion, Dionysius, Johannes, Martinianus, 

 and Konstantinus, in the reign of King Decius, 251, fled to the 

 mountains because they would not follow the Jewish religion. 

 In a mountain called Kalion, near Ephesus, they found a large 

 cave, into which they entered, slept, and ultimately became shut 

 in. It was not till theyear 446, under thereignofTheodosius, that 

 this cave was accidentally opened, and the seven sleepers woke 

 up from their long sleep of nearly 200 years, Bishop .Martinand 

 the king being both witnesses to this wonder. The Christians 

 died eventually surrounded with glory and honour. The saying 

 which has come down to us to-day, and which, curiously enough, 

 connects these holy men with the weather, is that, if it should 

 rain on June 27, we must expect rain for the following seven 

 weeks ; this is for the Roman Church. In the Greek 

 Church this day is held on August 4, while the " Acta Sanc- 

 torum " name July 27 for its remembrance. It may be of 

 interest, however, to see whether the application of this old 

 legend to the weather recently experienced holds good. 

 Taking the Roman Church Calendar as our reckoning, and 

 commencing on June 27, the seven weeks would then terminate 

 on August 14. Unfortunately rain did not happen to fall on the 

 27th at the place in question, but records show that both the day 

 before and after it was experienced. On the 29th and 30th also 

 no rain fell, but with the exception of July 6, 29, and 30, rain has 

 fallen daily until August 14. Thus from June 27 to August 14, 

 both days inclusive, a period of 49 days, only six days were 

 recorded without rain, but rain did not actually fall on the 

 27th. One infers from the legend that at the end of this 

 period fine weather should be the order of the day, that is to 

 say, if according to the " Sieben Btudern " it did not rain on 

 July 10. Unfortunately or not, as the case may be, i ^mm. on 

 200 square cm of rain were recorded, which means, according 

 to the latter legend, that it must rain for seven weeks after 

 this date. At the time of writing, -Vugust 24 (7 p.m. Central 

 European time), it has rained daily since the 14th, so that the 



NO. 1297, VOL. 50] 



//-A 



- is only of import- 



dt- 



" Sieben Briidem " seems as if it will be verified. The 

 meteorological records referred to above we owe to Herr A. 

 Sporhase, meteorological observer at the Physical Institute, 

 Gottingen. 



At a recent meeting of the Societe FraD9aise de Physique, 

 M. Bouty read a paper on the capacity of the capillary electro- 

 meter. The author supposes that the two quantities of 

 mercury are brought to a difference of potential e, and that the 

 surface of the mercury in the capillary is brought back to the 

 zero by increasing the pressure, and that a quantity of elec- 

 tricity (^Q is then suppliedjwithout changing the pressure. The 

 capacity of the apparatus, under these conditions, consists, 

 according to Lippmann's theory, of two parts, one term pro- 

 portional to the square of where A is the surface tension 



de 



and represents the quantity of electricity absorbed or produced 

 by the change in the form of the small surface of mercury, and 

 has the preponderating influence when e is nearly zero. The 



other term which is proportional to - 



ance when A is near its maximum. In order to measure the 



capacity C which is equal to — i the author measures separ- 

 de 



ately the corresponding values of 5Q and he within such limits 

 that proportionality exists between these quantities. He pro- 

 duces a constant quantity of electricity (5Q) by means of a 

 piezo-electric p'ece of quartz, and discharges it into the electro- 

 meter, whose capacity may be considered as infinite compared 

 to that of the quartz. He then determines by means of a deri- 

 vation on the circuit of the charging battery the increase le of 

 the electromotive force necessary to reproduce the same shift 

 in the mercury as was produced by 5ij. In every case the 

 observed values agreed with those deduced by means of Lipp- 

 mann's theory. 



M. W. Spring, who about fifteen years ago proved the 

 possibility of welding metallic bodies by simple pressure at 

 temperatures far below their fusing point, publishes an interest- 

 ing extension of his researches in the Bulletin de C AcaJlmie 

 Royale de Belgique. He was led to the conclusion that at a 

 certain temperature, where a metal is to all appearances a per- 

 fect solid, a certain proportion of the molecules attain a rate 

 of vibration corresponding to the liquid state, and that these 

 molecules, by softening the body, make it capable of welding 

 and of producing alloys with other metals. The metals were 

 put in the shape of cylinders bounded by plane surfaces, upon 

 the purity of which great care was bestowed. They were then 

 mounted in a stirrup, and pressed together by means of a hand- 

 screw. In this state they were placed in a heating oven, and 

 kept at a constant temperature between 200° and 400^ for from 

 three to twelve hours. The most perfect joints were produced 

 with gold, lead, and tin, and the worst with bismuth and anti- 

 mony. Two cylinders thus welded together could be put in a 

 lathe, one of them only being held in the chuck, while the 

 other was being worked upon by a cutting tool, without coming 

 apart. They could be separated with the aid of pincers, but 

 then a rough breakage was produced which did not coincide 

 with the original plane of separation. It appears that the more 

 crystalline the bodies are the less do they exhibit this pheno- 

 menon of incipient liquefaction, which begins to show in the 

 case of platinum, for instance, at 1600° below its fusing-point. 

 That such a liquefaction or softening actually takes place 

 was proved by cutting a delicate spiral 0'2 mm. deep on the 

 end surface of a piece of copper weighing 130 grammes, and 

 placing it upon a sheet of mica. After keeping it at 400° for 

 eight hours, the spiral had entirely disappeared, and the surface 

 looked as if just fused before the blowpipe. Where two 



