July 22, 1897] 



NATURE 



273 



successful prosecution has concomitantly increased. To 

 replenish the waste, artificial cultivation of the pearl- 

 oyster has been tried in various localities ; and of all 

 these, the author considers that the islands of Torres 

 Straits are the most likely to yield successful results. 



The last three chapters, respectively entitled " Marine 

 Miscellanea," "Insect Oddities," and "Vegetable 

 Vagaries," we are reluctantly compelled to pass by without 

 mention, although all merit the reader's best attention. 

 Were our notice extended to three times its length, even 

 then but comparatively few of the more interesting points 

 in this volume could be touched upon ; but as it is, 



Fig. 2.— Termite mounas, .'\ibany, North Queensland. 



enough has been said to indicate how well the author 

 has made use of his exceptional opportunites of observ- 

 ation, and in what an attractive guise he has presented 

 his results to the public. R. L. 



THE CALCUTTA EARTHQUAKE. 

 /^N Saturday, June 12, at almost precisely five o'clock 

 ^-^ in the afternoon, Calcutta was visited by a some- 

 what severe shock of earthquake, most sensational 

 reports of which, judging from the accounts that have 

 appeared in the Indian papers, were probably telegraphed 

 NO. 1447, VOL. 56] 



to England, and must have caused considerable anxiety 

 among those who have relatives or friends out here. As 

 a matter of fact few lives were lost, the warning given 

 by the preliminary tremors allowing every one ample time 

 to escape from their tottering dwellings, while in the 

 crowded native quarters of the city the damage done is 

 remarkably slight, the European quarter having suffered 

 most. This apparent partiality of the shock is not, 1 

 think, to be attributed to any difference in its severity 

 over the two areas, but rather to differences of construc- 

 tion and environment of the buildings. In the native 

 town the houses are, as a rule, low, and built close to- 

 gether, thus supporting each other, while the European 

 houses are generally detached, each standing in its own 

 compound, and very commonly three stories in height. 

 It is a notable fact that the only buildings greatly 

 damaged are old, mostly dating back to the beginning of 

 the century, or even older, and that they have already 

 been subjected to severe shocks of earthquake, and were 

 badly cracked. No new buildings have suffered in any- 

 thing like the same degree, and it is difificult to find a 

 crack anywhere that one can safely assume to have been 

 ! caused in the first instance by the present earthquake. 

 The common practice of the owners,, 

 after such a visitation, is to have the 

 cracks covered up by a thick coating 

 of plaster, so that to all appearance a 

 house is as sound as before. In many 

 cases this practice is being followed 

 out now, so that there is every pro- 

 spect of the next earth- 

 quake being attended 

 with still more disas- 

 trous results. 



In addition to the 

 faulty construction of 

 the buildings just men- 

 tioned, the damage 

 caused must be attri- 

 buted to the duration of 

 the earthquake, rather 

 than to any inherent 

 severity of the shock it- 

 self. Various estimates 

 are given as to the 

 duration of the shock, 

 ranging from four to 

 ten minutes, and it must 

 have lasted at least six 

 minutes. The most trustworthy observations give i6h. 58m. 

 (local time) as the time of commencement, while two of 

 I the observatory clocks at Adipur stopped, within a few 

 seconds of each other, at ijh. 4m. 22s. and lyh. 4m. 26s. 

 ; respectively. The buildings had thus ample time to take 

 up the impulses given to them by the vibration of the soil, 

 and after the earthquake had continued for a couple of 

 minutes or so, each building was rocking to and fro with 

 its own particular period of vibration, irrespective of the 

 period of vibration of the earth, which I do not think 

 ; varied much during the time it lasted. I happened to 

 be on the third story of a new building, which was not 

 ! damaged, at the time of the earthquake, and it seemed to 

 me (and my observation has been confirmed by others to 

 I whom I have spoken on the subject) that distinct nodes 

 were perceptible, during which, presumably, the vibra- 

 tions of the house and those of the earth interfered with 

 each other, and it is to the twisting effect produced by 

 the presence of these nodes that I would attribute most 

 of the damage done. It is curious that not a single 

 factory chimney was overturned, or even cracked, though 

 ; the chimneys rocked violently from side to side ; their rate 

 I of vibration probably synchronised more or less with 

 j that of the earth. On the other hand, three, at least, of 

 the church spires have broken off near the top ; but in 



