HARDWICKE'S SCIENCE-GOSSIP. 



259 



through the axis of the cone of Vesuvius, but all 

 the rest presented great diversities, and some, 

 when prolonged, would not touch the cone at all. 

 In making a lithological examination of the dykes 

 of Somma, the author directed particular attention 

 to the position of the elongated air-bubbles found 

 in the material of each dyke, considering that the 

 direction of the longest axis of these bubbles would 

 indicate the flow of the material when in fusion. 

 He stated that on the whole the long axes of the 

 bubbles are nearly horizontal or pointing at mode- 

 rate angles upwards in directions very nearly 

 parallel to the plane of the dykes at the place where 

 they occur. Hence he inferred that the dykes 

 were filled by injection, not from below, but nearly 

 horizontally. The author further referred to the 

 mineralogical characters of the materials of the 

 dykes, and stated that they are net all composed of 

 euciticlava; he also mentioned the occurrence of 

 cross columnar structure in some of the larger ones. 

 After referring to the differences observable in the 

 physical condition of the two surfaces of some 

 dykes, the author proceeded to consider the mode 

 of origin of the fissures which, when filled, con- 

 stitute volcanic dykes. He maintained that the 

 production of a fissure and its filling with molten 

 matter must have been simultaneous and due to 

 the same cause, namely, the hydrostatic pressure 

 of the liquid lava more or less filling the crater, 

 the pressure originating the fissure into which the 

 pressing liquid at the same time enters : a fissure 

 thus produced and filled will always be widest near 

 the crater, so that if the material of the cone were 

 perfectly uniform the dykes produced would be 

 wedge-shaped. But from the absence of this 

 uniformity and other causes, fissures commenced at 

 the interior and propagated into the mass of volcanic 

 cones can rarely be uniformly distributed round 

 the crater or produced in regular vertical planes in 

 a truly radial direction. Hence the author con- 

 cluded that it is unsafe to attempt to fix the posi- 

 tion of an ancient crater by means of the intersection 

 or concurrence of the lines of apparent orientation 

 of dykes alone. The author stated that the intru- 

 sion of volcanic dykes cannot so greatly influence 

 the slope of volcanic mountains as has been sup- 

 posed. 



NOTES AND aTJERIES. 



Entomological Phenomenon. — I came across 

 the following extract lately in the " Annual Regis- 

 ter " for the year 1771. It may interest some of 

 your entomological readers. It is contained in an 

 account of a dreadful famine in the neighbourhood 

 of Calcutta, written by a correspondent of Mr. 

 Urban, in the East-India Company's service, and 

 first published, apparently, in the Gentleman's 

 Magazine : — " In the month of August " (the writer 

 says, whose signature is J. C.) "we had a very 



alarming phenomenon appeared (sic) of a large 

 black cloud at a distance in the air, which some- 

 times obscured the sun, and seemed to extend a 

 great way all over and about Calcutta. The hotter 

 the day proved, the lower this cloud seemed to 

 descend, and for three days it caused great specula- 

 tion. The Brahmins pretended that this phenomenon, 

 which is a cloud of insects, should make its appear- 

 ance three times ; and if ever they descended to the 

 earth, the country would be destroyed by some 

 untimely misfortune. They say that about 150 

 years ago they had such another bad time, when 

 the ground was burnt up for want of rain. This is 

 the second time of this phenomenon's appearing, 

 and that they came much lower than is recorded, of 

 the former. On the third day, the weather being 

 very hot and cloudy, with much rain, we could 

 perceive them with the naked eye, hearing a con- 

 tinual buzzing. About one o'clock they were so 

 low as 30 feet from the ground, when we saw them 

 distinctly to be a great number of large insects, 

 about the size of a horse-stinger, with a long red 

 body, long wings, and a large head and eyes, keep- 

 ing close together like a swarm of bees, seemingly 

 flying quite on a line. I did not hear of any that 

 were caught, as the country people were much 

 frightened at the prognostications of the Bramhins. 

 Whilst it rained, they continued in one position for 

 near a quarter of an hour ; then they rose five or six 

 feet at once, and in a little time descended as 

 much, until a strong north-west wind came and 

 blowed (sic) for two days successively, when they 

 gradually ascended and descended in the same 

 manner, but more precipitately, until next morning, 

 when the air was quite clear. It was very remark- 

 able that for some days before the appearance of 

 this phenomenon the toads, frogs, and insects, 

 which in numbers innumerable always make a con- 

 tinued noise here the whole night, during the rains 

 disappeared, and were neither seen nor heard 

 except in the river." This famine, according to 

 the above writer's account, was most terrible. The 

 cause is by him attributed to the English engrossing 

 large quantities of rice in anticipation of a bad crop, 

 and to the native granaries at Calcutta being burnt 

 down. 



Colour of Birds.— Can I find out, through the 

 medium of Science-Gossip, what other British 

 birds besides the following have been found white 

 or ivory - coloured ? Jay (Garrulus glanclius), 

 cuckoo (Cuculus canorus), common thrush (Turdtts 

 musicus), blackbird (Tardus merula), skylark 

 ( Alauda arvensis), tree-sparrow (Passer montanus), 

 house-sparrow (Passer domestic/is), rook (Corvus 

 frugilegus), woodcock (Scolopax rusticola), gold- 

 finch (Carduelis elegans), bullfinch (Pyrrhula vul- 

 garis), chaffinch {Fringilla ccelebs), jackdaw (Corvus 

 tnonedula), starling (Stumus vulgaris), swallow 

 (Hirundo rustica), are all to my knowledge. I 

 should be very glad if any of your readers could 

 add any more to this list, and say where they are to 

 be seen. — A. P. 



The Cuckoo's Eggs.— The late Bishop Stanley, 

 in his "History of Birds," vol. ii. p. 77, says:— 

 " The Cuckoo can build a nest, and rear its young 

 ones as well as another; for a clergyman near 

 Glossop, in Derbyshire, not only saw a cuckoo rise 

 from its nest, built on the stump of a tree, but _ in 

 it found two young ones ; and by way of ascertain- 

 ing whether they were under the care of the real 

 or foster parents, he confined one of them to the 

 nest, and for many days saw the old cuckoo feed it 



