136 



HARJDWJCKE'S SCIENCE-GOSSIF. 



The third Report of the United States Entomo- 

 logical Commission, relating to the Rocky Mountain 

 locust, the western cricket, the army worm, canker 

 worms, the Hessian fly, together with descriptions of 

 larvae of injurious forest insects, studies of the embryo- 

 logical development of the locust and other insects, 

 &c., has just been issued from the United States 

 printing office. The chief contributors are Messrs. 

 Riley, Packard, and Thomas, who have turned out a 

 useful and handsome volume. 



The International Food and Health Exhibition 

 was opened by the Duke of Cambridge on May 8th, 

 in the building occupied last year by the Fisheries 

 Exhibition, the aquarium of which is still in working 

 order and on view. 



The Linnean Society of New South Wales have 

 offered a prize of ;[Cioo for the best essay on "The 

 Life- History of the Bacillus of Typhoid Fever." 



In the Transactions of the New Zealand Institute, 

 Mr. J. A. Pond describes the occurrence of a vein 

 of Platinum, in octahedral crystals, associated with 

 quartz in the Thames gold district. 



A naturalists' society has been 'formed at 

 Clevedon, Somersetshire, for the study of the fauna 

 and flora of the neighbourhood, and the formation 

 of a local museum. President, Sir E. H. Elton, 

 Bart., Clevedon Court ; hon. secretary and curator, 

 R. J. Morgan Esq., Wellington House, Clevedon. 



It will be remembered that the Dutch Government 

 appointed a commission to investigate the nature and 

 results of the eruption at Krakatoa, in August last. 

 The Report has just been presented by Dr. Verbeek, 

 and it is a remarkable illustration of scientific courage 

 and adventure. At the same time it shows that the 

 eruption was on a scale which might almost be called 

 catastrophic. Krakatoa lies on a rent or fissure in 

 the crust of the earth which runs across the Straits of 

 Sunda. Dr. Verbeek thinks that sea water may 

 have been admitted thus to the molten matter 

 beneath, so as to form steam at high pressure. The 

 sound of the volcanic explosion of August last was 

 heard over a space equal to one-sixth of the earth's 

 circumference. So violent were the air-waves caused 

 by the explosion that walls were rent by them (not 

 by earthquakes) at the distance of 830 kilometres 

 away. One air-wave was propelled from Krakatoa 

 which travelled no less than three and a quarter 

 times round the circumference of the earth. The 

 large tidal wave appears to have been caused by the 

 northern part of the mountain giving way. There 

 only remains the southern part, which has been cut 

 in two from the very top, and forms on the north side 

 a magnificent precipitous cliff more than 2,500 feet 

 high. In the place where the fallen part once stood 

 there is now everywhere deep sea, in some places as 

 much as 1,000 feet deep. The ashes thrown out by 

 the eruption must have been enormous, especially if 



we are correct in assuming the brilliant sunsets are 

 due to the finer parts suspended in the atmosphere. 

 Within a circle of fifteen kilometres' radius from the 

 mountain, the layers of volcanic ashes thus ejected 

 cover the ground from 60 to 80 metres thick. The 

 known surface over which the ashes were projected, 

 as calculated by Dr. Verbeek, is 750,000 square 

 kilometres — apart from other unknown areas where 

 they also descended. He thinks that the finer 

 particles, propelled by the wind, have made a journey 

 round the world. The vapour was condensed to 

 water, and froze in the cold currents. The refraction 

 through these innumerable ice crystals. Dr. Verbeek 

 thinks, caused the beautiful and red glows of our 

 phenomenal sunsets. He calculates that the quantity 

 of solid substances ejected by the volcano was 18 

 cubic kilometres. Dr. Verbeek and his staff 

 thoroughly explored the island last October, when 

 the heat was so great as almost to stifle them. 



MICROSCOPY. 



Improvements in Microscopic Slides.— Mr. 

 B. Piffard has obtained a patent specification under 

 the above title, and has sent us a slide made in 

 accordance with it as a sample. A round recess is 

 made in the glass slip of the necessary depth. In 

 this the object to be mounted is placed, and covered 

 with the usual thin disk of microscopic glass. In 

 this way the upper surface is perfectly smooth, as the 

 surface of the disk is even with that of the slip. 

 No danger occurs, therefore, of the cover-glass and 

 object being knocked off ; and the hollowing of the 

 recess, which is done by means of a diamond, causes 

 a very beautiful diffusion of light, such as we have 

 not noticed in ordinary mounts. For beauty of finish 

 and neatness, there can be no doubt that Mr. Piffard's 

 plan is superior to any yet brought out. 



Journal of the Royal Microscopical Society. 

 ^The April part of this welcome and excellently 

 edited serial contains besides the current researches 

 relating to zoology, ^botany, and other departments 

 of microscopical research, the following papers : 

 "Observations on the Life- History of Stcphanoccros 

 Eickornii" (illustrated), by Mr. T. B. Rossetter ; 

 the President's Address, by Professor Duncan ; " On 

 the Mineral Cyprusite," by Julien Deby ; "List of 

 Desmidieaj found in Gatherings made in the Neigh- 

 bourhood of Lake Windermere during 1883," by 

 Mr. J. P. Bisset; and on "The Formation and 

 Growth of Cells in the Genus Polysiphoiiia," by 

 Mr, George Massee. 



The Markings on Test Diatoms.— These have 

 always been a bone of contention amongst micro- 

 scopists, some considering them depressions, whilst 

 others affirm that tjiey are elevations. Twenty years 



