October 4, 1900] 



NA TURE 



555 



world. As compared withjthe mountains of Java or Sumatra, they 

 are civilised, and have a much more salubrious climate and all 

 the conveniences of modern civilised life. The south island of 

 Hawaii or the South Pacific Islands have no such stretches of 

 virgin forest, or such a flora or fauna ; to explore Ceylon is hot 

 and uncomfortable in comparison ; and the mountains of Jamaica 

 and Trinidad are uninhabited except by scattered planters. 

 Prof. Fairchild reckons the hotel expenses at Petropolis as about 

 two dollars per diem. 



Frequent as earthquakes are in the Philippine Islands, 

 those of the year 1897, being unusual both in number and in 

 violence, form the subject of an important memoir by P. Jose 

 Coronas, which we have just received from the Observatory of 

 Manila. He estimates the total number of shocks at 307, occur- 

 ring in 108 groups. No part of the archipelago was entirely 

 free from earthquakes, though less than five were felt in 

 Mindoro, Paragua and the central part of Luzon. In the north- 

 east of Samar, where more than a hundred were felt, they were 

 most frequent and most destructive. Full descriptions are given 

 of the three most important earthquakes — those of Luzon, 6n 

 August 15 ; Zamboanga, on September 21, with the accompany- 

 ing sea-waves and long series of after-shocks ; and Samar, on 

 October 19-20. Four of these earthquakes were recorded at 

 distant stations, both Shide and Edinburgh being more than 

 11,000 kms. from the origins. The mean velocities of the waves 

 of the two principal Zamboanga earthquakes are estimated at 

 87 and S'l kms. per second along the surface, or 7-6 and 7-1 

 kms. per second along the chords. 



Determinations of the rate of increase of underground 

 temperature, apart from their scientific interest, have an important 

 practical application in fixing the limit of depth at which mining 

 operations can be carried on successfully. In this connection a 

 report has been lately issued by the Department of Mines of the 

 Government of Victoria, dealing with observations of under- 

 ground temperature at Bendigo, the author being Mr. James 

 Stirling, Government Geologist. The rise of temperature of the 

 rocks with the depth varies in different parts of the earth's sur- 

 face, thus making it difficult in any mining district to determine 

 what the rate of increase is without actual experiment. Thus, 

 if we accepted the hitherto recognised formula for the Bendigo 

 field of 1° Fahr. for every 60 feet in depth, we should have a 

 temperature of 125° at the 3,500 feet level. The observations 

 already made prove that this temperature is not reached. It 

 has been asserted in some quarters that mining might extend to 

 as great a depth as 10,000 feet, if the difficulties of haulage 

 could be overcome ; but when we consider the effect of com- 

 pressing the air at such a depth {i.e. the compression caused by 

 its own weight), it will be seen that ventilation under ordinary 

 conditions would be practically unattainable. At a depth of 

 10,000 feet the ventilating current entering the shaft at, say, a 

 temperature of 60° Fahr., would attain a temperature of 90° by 

 its own weight, altogether apart from the additional heat 

 acquired by contact of the air with the heated rock surfaces. It 

 is possible, however, to imagine a limit of 5000 feet as a work- 

 able depth, although the present observations as to the normal rate 

 of increase of temperature of the rocks at Bendigo— 1° Fahr. for 

 every 135 feet— suggest 4000 feet as a convenient practical limit 

 to healthy working. Mr. Stirling's report is accompanied by 

 charts illustrating the temperature and pressure gradients in No. 

 180 mine. In connection with the composition of the air, Mr. 

 Stirling calls attention to the very defective ventilation of many 

 mines, and to the necessity of owners and directors of mines 

 taking steps to remedy the existing evils. 



In Nature, vol. lix. p. 133, we briefly referred to the very 

 interesting investigations of MM. Hildebrandsson and Teisserenc 

 de Bort into the history and present conditions of dynamical 

 NO. 1614. VOL. 62] 



meteorology. Part ii. of this important work has now beert 

 issued, dealing generally with revolving storms, and the organi- 

 sation of the international meteorological services, and particu- 

 larly with the parts taken by Le Verrier, FitzRoy, and Buys 

 Ballot, and reproducing specimens of the earliest reports and 

 charts issued by each. Le Verrier seems to have been the first 

 in Europe to conceive the idea of telegraphic weather fore- 

 casts, although, owing to inadequate support, he was the last 

 of the three to introduce a regular working service. It is 

 interesting to read, thirly-five years after the death of Admiral 

 FitzRoy, the judgment of the eminent authors upwn his work 

 in this country, viz. that the criticism of his weather service was- 

 both severe and unjust, and Le Verrier's opinion is quoted that 

 if he did not arrive at sufficiently practical results, probably oi> 

 account of the limited area dealt with, no one else in his place 

 could have done better. In another chapter, dealing with the 

 fundamental works in the different countries between 1865 and 

 1872, the laborious investigations of Dr. Buchan occupy a pro- 

 minent place. The publication of his remarkable memoirs and 

 charts at this early epoch were of the highest importance in the 

 development of dynamical meteorology, and the early researches 

 made subsequently in other countries have been, to a great 

 extent, simply verifications of his ideas. The Storm Atlas of 

 Prof. Mohn, the present chief of the Norwegian Meteorological 

 Service, the publications of the Meteorological Office, and the 

 Synoptic Charts of the late Captain Hoffmeyer and of the 

 Copenhagen and Hamburg institutes, are also specially referred 

 to as having contributed greatly to the development of meteoro- 

 logical science. 



The remarkable colour-changes exhibited by a familiar praivn 

 {Hippolyte variaiis) form the subject of an extremely interesting 

 and most beautifully illustrated paper by Dr. Gamble and Mr. 

 Keeble, which appears in the Quarterly Journal of Micro- 

 scopical Science for September. The species in question may be 

 met with commonly in the lower tidal pools along the shore, or 

 may be obtained by trawling in deeper water. It has long been 

 known that difterent individuals exhibit variations in colour 

 ranging from one end of the spectrum to the other, and also that 

 many specimens display a protective resemblance to the particular 

 seaweeds on which they may be resting. It is now demonstrated 

 that all the different colour-variations are capable of passing 

 into one another, and the protective resemblances of individuals 

 to their environment are most admirably displayed in the coloured 

 plates with which the paper is illustrated. But this is not all. 

 Twice during the twenty-four hours every specimen is living in 

 deeper water than ordinary, and this includes a certain change 

 in coloration to harmonise with the stronger or weaker light. 

 But a much more important colour-change is induced by the 

 daily alternation of light and darkness, and as the shades of 

 evening approach every single individual of the species gradually 

 loses its distinctive diurnal hue and becomes of a full trans- 

 parent azure blue. The change is heralded by a reddish glow 

 followed by a green tinge, which finally melts into the azure. 

 And it is not a little remarkable that the day-and-night change 

 has been so long established that it has become periodic and 

 occurs whether the specimens are kept in perpetual darkness or 

 vice vend. 



To the same journal Monsieur E. L. Bouvier communicates 

 a supplemental paper on the results of his examination of the 

 series of examples of Peripatus in the British Museum. He 

 deals especially with the specimens described as P. jamaicensis, 

 which are shown to include two perfectly distinct species. 



Our German contemporary, Nalurwissenschafiliche IVochen- 

 schrift, ol September 23, contains a long digest of Prof. G. 

 Siebert's translation of Lydekker's " Geographical History of 

 Mammals," which was published so long ago as 1897. 



