Feb. 19. 1885] 



NA 7 URE 



361 



being of a peculiar type, even when too far from the sun to 

 show any colour. The clouds thus coloured are usually of a 

 much striated or rippled structure, and show the colours gene- 

 rally in small spectra ; whereas the clouds seen in December 

 were remarkably smooth in texture, and although often striated, 

 the striations were feeble and comparatively few, and in straight 

 lines, while each cloud showed one regular gradation of colour. 



Whether the coloured clouds described by your correspond- 

 ents, with the exception of those mentioned by Mr. N., were 

 all of the same kind, it is difficult to decide; perhaps they may 

 have been so, in spite of the varieties in their appearance. Some 

 observers describe the body of these clouds as having been dark, 

 in particular your correspondents at Darlington and Broseley 

 (Shropshire), pp. 192, 193, whereas all seen here were white or 

 bright. Still, those clouds seen further south were probably of 

 the same kind, only thicker. The difference in shape is most 

 likely not a radical one, as the larger clouds seen here had wavy, 

 not straight, edges, though their general directions were the 

 same as the sides of the more rectangular ones. The nearest 

 approach here to a pallium of these singular clouds was on the 

 morning of December 12, when there occurred, at 8.15 a.m., an 

 extensive pale steel blue film above the region where the sun 

 was, and reaching to an altitude of 25 . 



Dr. H. Geelmuyden, observing at Christiania on December 8 

 (see p. 264), appears to place the peculiar clouds at a lower level 

 than cirro-cumulus, but as seen here they were [always the 

 highest clouds. 



In conclusion, I think that Prof. A. S. Herschel is mistaken 

 in supposing these clouds have been " only a good instance of a 

 common sight," but although I never noticed them before, I do 

 not dispute the suggestion of Dr. Geelmuyden that they may be 

 seen more frequently than some ofj.us have thought. I have not 

 seen them since December 13. T. W. Backhouse 



Sunderland, February 11 



Human Hibernation 



I DID not answer your correspondent's query on human 

 hibernation in your issue of the 5th inst. (p. 316), because I 

 thought some one better informed than myself would answer it. 

 However, as no one has done so, I may as well give a solution 

 of this well-known Indian trick which I have seen, but the 

 authority for which, I am sorry to say, I cannot remember. It 

 is very simple, like all these things are when you "know how 

 they are done." A tunnel is dug from the grave to the neigh- 

 bouring jungle ; the grave itself is partly prepared. The subject 

 is then, in sight of the spectators, prepared, by having his ears 

 and nostrils filled with wax, and his tongue turned back. He 

 is then apparently buried, creeps through the tunnel, and gets 

 away. After six months, or any other interval, he creeps back 

 again, is dug up apparently lifeless, and restored with infinite 

 pains. In some cases, I believe, a sentry has been placed over 

 the grave, but, of course, without results 



Alfred II. Hulk 



Bolney House, Ennismore Gardens, S.W., February 13 



An Error in Ganot's "Physics" 

 I beg to call attention to a typical error in a formula which 

 appears to have run through ten editions of Ganot's well-known 

 treatise. It is one not difficult of discovery by that somewhat 

 too rare class of students who carefully plod through all the steps 

 which lead up to it, but very likely to be overlooked by the more 

 common class who are content to extract the formula as it stands 

 with the undoubting faith reasonably based on " Tenth Edition, 

 revised and enlarged." 



The formula which represents the weight of air saturated with 

 vapour occurs on p. 325 of the tenth edition, and is printed — 



(1 + 0/(760 s ; 



The first /"should obviously be expunged. 



E. Douglas Archibald 

 Tunbridge Wells, February 16 



Shadow on Clouds 

 I am not aware if the following phenomenon is at all common, 

 but I venture to think it somewhat unusual, and that it might 

 nterest some of your readers : — 



Whilst at anchor in Cumberland Bay in the Island of Juan 

 Fernandez on the evening of December 24, 1884, we observed 

 the following remarkable sight. The Bay is situated on the 

 north side of the island, and some way inland is a remarkable 

 hill, called the "Yunkua," or "anvil," it being somewhat of 

 the shape of one ; it is the highest hill in the place, viz. 

 3005 feet, and from the anchorage bears about south-west, and is 

 distant two miles. The Bay is closed in by high cliffs and hills. 

 On the day mentioned, shortly after the sun had disappeared 

 behind the western hills, we observed this hill make a distinct 

 shadow on the clouds above it, in which every irregularity and 

 peak came out with wonderful clearness. The shadow lasted 

 till about 30" before the time of sunset (which was Invisible to 

 us), and was inverted and inclined to the hill as in a mirage at 

 about 30 . The weather at the time was very fine. Barometer, 

 30"22 ; temperature of altitude thermometer, F. 62 ; and very 

 few clouds were about. Alfred H. Tarleton 



H. M.S. Constance, at Sea, January 25 



THE METEOROLOGY OF HAVANA J 

 '"THIS annual of the Royal College of the Society of 

 -*■ Jesus at Havana for 1875, which has just been pub- 

 lished, possesses more than a passing interest. The 

 Observations were made daily every two hours from 

 4 a.m. to 10 p.m., and include pressure, temperature, 

 humidity, wind, rain, magnetic, electric, optical, and other 

 weather phenomena. The results are plotted on large 

 monthly diagrams, and as each day has six-tenths of an 

 inch devoted to it, the two-hourly observations of all the 

 different elements can be readily seen and compared with 

 each other ; and this part of the work is done with a~ 

 scrupulous care and accuracy it would not be easy to sur- 

 pass. On the same diagrams are marked the days on 

 which auroras are reported to have been observed in the 

 United States, as published in the Monthly Weather 

 Review at Washington. 



A note is appended to each month's observations, draw- 

 ing attention to the more significant of the magnetic 

 perturbations in their relations to the changes of weather 

 at the time, and in particular to the " nortes," or " nor- 

 thers," of the cooler months of the year. Thus, on April 

 3, 4, and 5a" norther " prevailed, which was succeeded; 

 on the three following days by a remarkable magnetic 

 perturbation, which was accompanied with a high baro- 

 meter and a strong wind, rising in the afternoons to a rate 

 of 35 kilometres per hour, with daily manifestations of 

 aurora in the United States, but was unaccompanied 

 throughout with any electric phenomena. Again, the 

 magnetic perturbation, of April 13 was coincident with a 

 characteristic " norther," much thunder and lightning, a 

 very heavy rainfall, and a disposition and state of the 

 aqueous vapour which give rise to solar and lunar halos, 

 and other optical effects ; but during the time no auroras 

 were reported from the United States. Father Vines 

 points out in the monthly notes various other relations 

 between the magnetical and meteorological phenomena 

 which suggest that this line of inquiry is likely to lead to 

 valuable additions to our knowledge of weather changes, 



The mean annual pressure at sea-level is 30x167 inches, 

 the maximum being 30-129 inches in January and the 

 minimum 30-002 inches in September, with a secondary 

 maximum of 30-092 inches in July and minimum of 30x166 

 inches in April. As regards the diurnal oscillation from 

 the morning maximum to the afternoon minimum, the 

 greatest occurs in the winter months, when it amounts to 

 o'oSo inch, whereas in July it is only 0-051 inch. These 

 diurnal and seasonal fluctuations in their varying amounts 

 have no small significance in their relations to the 

 analogous phenomena in the United States and over the 

 high pressure area of the Atlantic. The mean annual 

 temperature is 77°7, rising to the maximum 82 0, 2 in July, 

 and falling to the minimum 73°'o in December. The 



' " Observations Magnfticas y Meteonilogicas del Real Colegio de Belen 

 de !.i Compafiia de Jesus en fa Habana. Ano de 1875." (Habana, 1884.) 



