28o 



NA TURE 



[J AN LAKY i7, 1895 



A FURTHER instalment of M. Raoul PiCtet's fascinating ex- 

 periments at very low temp:ratu-es is published in the Comptes 

 renJut. The object of the eicperiments was to test the power 

 of cotton-wool and other bad conductors to prevent the passage 

 of loT-temperature radiation. Copper cylinders were cooled 

 down to — 170° C. and packed in layers of cotton-wool of 

 various thicknesses. It was found that the cylinders rose to 

 about - So° very ripidly, and that the rate of warming was 

 the same whether the cylinders were naked or packed in cotton- 

 wool of 20 inches thick. The " bad conductor " behaved, in 

 fact, like a perfect conductor transparent to heat radiation. 

 Above - 80 the influence of the packing began to make itself 

 fell, the rn'e of warming varying with the thickness of the 

 layer. 



Ix the current number of Statural Science, Captain Marshall- 

 Hall urges the importance of a fuller study of existing glaciers, 

 as the necessary bisis for any attempt at setting in order the 

 chaos of opinion on the nature and causes of the Glacial 

 period. He gives an ace mnt of the steps recently taken by 

 the .Alpine Club and the Glacier Committee of the International 

 Geological Congress towards drawing up a systematic statement 

 of the methods of observation, for the use of those who can 

 visit and examine modern glaciers in any part of the world. 

 For fuller details, readers are referred to papers in the Alpine 

 fournal (February 1S91, and November 1894) ; but a number 

 of subjects for careful observation are suggested, and some 

 necessary precautions mentioned. It is very satisfactory to see 

 that the members of the Alpine Club, if primarily climbers, 

 are able incidentally to do useful service to Geology. 



In the last number of tlie Records of the Geological Survey 

 of India, Dr. Noetling announces an interesting discovery from 

 Baluchistan. Certain beds which Mr. Oldham had recently 

 described as in'ermediate betwieci Cretaceous and T,erliary he 

 finds really belong to th • Danian — a stage to which the English 

 chalk nowhere reaches (except perhaps in Norfolk), but which 

 forms the summit of the Cretaceous in various parts of Europe. 

 In examining the Echinoids from the Biluchisl.in beds. Dr. 

 N>etling found a striking resemblance to those fr)m the Danian 

 beds in the Pyrenees. That the Pyrenein fauna should resenble 

 that of such a distant region more than the nearer ones of 

 Northern Europe, is another of th;many pieces of evidence of 

 ancient life-provinces — not improbably climatic in this case — 

 that accumulate as geological research is extended into distant 

 parts of the world. It must be coupled with the further fact 

 that the Baluchistan Echinoids have little in common with those 

 of the same age in Southern India. 



The last number of the Comptes rendut contains a paper by 

 R. Colson, on the conditions which have to be fulfilled in order 

 to obtain correct results when measuring liquid resistances with 

 alternating currents and a telephone. Tne author, while work- 

 ing on the propagation of electrical waves of slow period, 

 obtained results which have an important bearing on the above 

 method of measuring liquid resistances. The results obtained 

 depend on the suppoiition thai, even in the case of alternating 

 currents in liquid resistances, Ohm's law holds. However, this 

 la V does not hold good in the case of the propagation of waves 

 of high potential, such as are furnished by the secondary of an 

 induction coil in high resistances, such as threads saturated with 

 a solution of calcium chloride, or capillary tubes filled with 

 water. The author gives a series of tests which, when applied 

 to any given arrangement of conductors, will show whether the 

 above cfTecls will have any influence on the result. 



Mk. B. D. Peirce has contributed a paper to the American 

 f'Urnal of Science (vo\. xlviii. p. 312), on the thermo-electric 

 properties of platinoid and manganine. Since plitiaoid and 

 NO 1316 VOL. 51] 



manganine wires are often used in potentiometers and slide 

 wire Wheatstone's Bridges, the thermo-electric properties of 

 these metals are of considerable interest. The author has 

 primarily determined the electromotive force of the above 

 metals and copper, since this is the most interesting case from 

 a practical point of view. He finds that after the manganine 

 wire has been well annealed, the thermo-electric phenomena 

 are quite regular. While the mean electromotive force for a 

 difTerence of 10° C. between the hot and cold junctions of a 

 copper manganine couple is about 55 microvolts, in the case 

 of a platinoid-copper couple the mean electromotive force for 

 the same difference of temperature is about 170 microvolts. 

 Incidentally the author has examined the thermo-electromotive 

 force of couples consisting of different samples of commeicial 

 copper, and he finds that two specimens of annealed copper 

 wire bought from different makers hardly ever yielded more 

 than one or two C.G.S. units of E.M.F. per degree Centigrade. 



-A FEW particulars concerning the earthquake felt in Nicar.igua 

 and Honduras in November 1S94, have been sent to us from 

 Managua, by Mr. J. Crawford. Shocks were felt for twenty 

 seconds at Managua, about gh. 36,n., and another series, 

 lasting about thirty seconds, at eleven in the evening of 

 November 19. Mr. Ciawford h.as been able to trace the course 

 of the waves for about 1 20 miles to the north-west and south- 

 east of the city. At Managua, the undulations were short and 

 rapid ; they were stronger at the city of Malaya — twelve miles 

 to the eastward, and still stronger at Granada — about twenty- 

 four miles east Aard. In the latter place, houses were thrown 

 down by the vibrations, and also at Chinandega — seventy 

 miles west of Managua, though at Managua itself the shocks 

 were not of sufficient severity to fracture any of the walls of 

 the houses, or displace any of the tiles on the roofs. It is 

 remarkable that the earthquakes were most violent both east 

 and west of the city. 



Mr. I. C. Shensto.ne has taken a census of remarkable oak 

 trees in Essex, and he gives, in the Essex Nattirjlist, de- 

 scriptions and illustrations of noteworthy specimens found by 

 him ; together with notes on a few oak trees outside the county 

 The five tiees with the largest trunks in Great Britain, stated in 

 "Loudon's Arboretum," are: Cowthorpe Oak, Yorkshire, 

 78 feet ; Merton Oak, Norfolk, 63 feet ; Hempstead Oak, 

 Essex, 53 feet ; Grimstone Oak, Surrey, 48 feet ; Salsey Oak, 

 Norlhampton, 46 feet. Among trees having the widest stretch 

 of boughs, are the Worksop Oak, 180 feet : and the Oakley Oak, 

 1 10 feet. All these trees are not, however, standing at the 

 present time. The Hempstead Oak fell about twenty-five 

 years a^o, and a mutilated and decayed tru ik is all that remains 

 of this forest giant. A fine tree, thirty-one feet in circumference, 

 exists in the park at D.inbury Palace. Tne inside of the bole 

 was completely burnt out more than sixty years ago, but the 

 tree has continued to grow, an I will probably yet survive many 

 years. Several of the trees mentioned arc said to be from five 

 hundred to a Ih msand years old, but there is not sufficient 

 evidence to decide the point at all accurately. 



British ornithologists have long been aware that the in- 

 crease and extension of r.inge of the starling presents some 

 interesting and phenomenal facts. They will therefore follow 

 with interest a paper on the increase and dislriliution of the 

 bird in .Scotland, contributed by Mr. J. A. Haivie-Brown to 

 the Annats of ScollisU Natural History for January. By look- 

 ing up old records dating back to the end of last century, and 

 by collecting information through a special circular, it has been 

 possible to give a consecutive statement of the steps of advance. 

 The account, and the m.ip accompanying it, show that, as re- 

 gards Scotland, the starling is almost omnipresent. The statistics 



