Sept. 5, 1889] 



NATURE 



447 



■during the early months of the present year the temperature was 

 'high and the rainfall small, and from the reports received by 

 •fhe Agricultural Department the infested area has largely 

 increased in England. In Scotland it does not appear to have 

 •made so much progress. Still it is present in many Scotch 

 •counties. The actual amount of injury to the crops is slight, 

 and, so far as can be ascertained, is not in any instance so 

 important as that caused in some cases in 1887. It is most 

 probable that the injurious operations of the insect have been 

 checked by the wet, cold weather which has followed the 

 abnormal heat of May, and the warmth and dryness of June. 

 When a cycle of hot summers occurs, it may happen that the 

 ravages of the Hessian fly may be general and calamitous. Mr. 

 Whitehead therefore urges the desirability of careful watching 

 and the prompt adoption of simple methods, which he describes, 

 for preventing the increase of the pest. 



The Industrie Textile has a long account of the treatment of 

 wild silks (that is, those which are furnished by silkworms other 

 than those of the domesticated Bomhyx mori) in their native 

 countries. In India there are no less than fifty varieties of silk- 

 tearing insects, the most irrportant of which is called tussur, 

 that is, "the weaver's shuttle." The caterpillar, like the moth, 

 is of a great size, and feeds upon more than thirty species of 

 plants. The cocoons of the tussur, which make their appear- 

 ance twice in the year, are found attached to the branches of 

 trees in the jungle in large oval masses. The caterpillar lives 

 from thirty to forty days, and then weaves its cocoon. In four or 

 six weeks from this time the moth comes out and lays eggs 

 from which comes a second generation of caterpillar. These 

 wrap themselves in the cocoon, and remain hanging to the trees 

 throughout the rainy season — that is, for seven or eight months. 

 The cocoon, which is about four times the size of that of the 

 mulberry silkworm, is composed of a double and interrupted 

 thread of abiut 1400 metres in length. The thread is im- 

 pregnated with uric acid of sodium, which must be removed by 

 the aid of an alkaline wash before the thread is unwound. The 

 tussur is tended with great care ; in fact, for centuries various 

 religious usages have been employed in rearing it. The moth, 

 which is a large insect of a brownish colour, having its wings 

 beautified by four transparent eyes, is venerated, and may be 

 only approached by people of a certain caste. Unlike the 

 tussur, which has been domesticated in India for some thousands 

 of years, the cocoons of the other species are collected in the 

 jungle. Amongst these is the Attacus cynthea, which feeds on 

 the castor-oil plant, and of which the cocoon is white. Other 

 species are the Anthercca assaina and the Cricula trifenestra, 

 which lives on the mangrove tree and spins a cocoon of a bright 

 golden colour. The most important Chinese species is the 

 Anthercea pernyi, which is cultiva'.ed in the province of 

 Sze-chuan. In China also is found the most beautiful of all 

 moths, the Attaais, alias, which spins an enormous cocoon, 

 covered at both ends with a very thick silk, known as Fagara 

 silk. In Japan are the Ailanthus caterpillar, and the Yamanai, 

 which till lately was reserved for the exclusive use of the Mikado, 

 and the exportation of the eggs was an offence punishable with 

 death. At present attempts are being made to cultivate this 

 species in France, and it is believed they will be successful. 



Messrs. Blackie and Son will publish immediately a trans- 

 lation of the well-known " Organische Chemie " of Prof. 

 Bernthsen, of Heidelberg. The translation is by Dr. George 

 McGowan, University College, Bangor, and the origin".l text 

 has been specially brought up to date for this edition by the 

 author, who has throughout shown keen practical interest in the 

 perfecting of the English edition. 



The Royal Meteorological Institute at Utrecht has just 

 published a valuable atlas of twenty-two charts, containing the 



results of observations in the Indian Ocean, for the separate 

 months of December, January, and February. Some portions 

 of the ocean are naturally without data, but the amount of 

 material dealt with may be judged of from the fact that 51,799 

 observations have been used in the construction of the wind 

 chart for December. The temperature of the sea-surface is 

 represented by isotherms drawn for every 2° C, and shows io 

 certain regions, e.g. near the Cape of Good Hope, considerable 

 differences of temperature in the various months. The currents 

 are plotted in 1° squares, in two colours, showing the re- 

 sultants of the currents setting towards the west and of those 

 towards the east, separately, together with the number of 

 observations from which they are calculated. Atmospheric 

 pressure is represented by isobars drawn for every 2 '5 mm. They 

 show an area of high pressure between lat. 30" and 35" S. and 

 long. 80° and 90° E. ; in January there are two centres of high 

 pressure, at long. 55° and 85°. The temperature of the air is 

 exhibited by isotherms for every 2° C. The difference between 

 the air and sea temperature is generally small, but the excess 

 of the latter sometimes amounts to 5° C. The wind is repre- 

 sented by roses showing the relative frequency for direction 

 (only), arranged according to homogeneous areas, combining 

 the same prevalent winds in irregular spaces. Other charts 

 show specific gravity, rain, percentages of storms, and other 

 interesting information. 



The third session of the Edinburgh University Extension 

 Summer Vacation Course was held, as before, during August, at 

 Granton Marine Station, through the kindness of Dr. Murray, 

 Director of the Challenger Expedition, and of Mr. Irvine, of 

 Royston. The courses of botany and zoology were conducted, as 

 last year, by Prof. Geddes and Mr. G. A. Thomson. This year 

 each course was divided into an elementary and an advanced 

 section, the former dealing with Vertebrates and Phanerogams, 

 the latter with Invertebrates and Cryptogams. Prof. Geddes 

 also delivered a course of twenty lectures on sociology. Some 

 twenty-five or thirty students attended. All the courses were 

 supplemented by demonstrations in the field and on the shore, 

 and by visits to public and private gardens and to the 

 Museum. 



In the abstract of Dr. Stefan's paper on "Ice Growth" 

 (Nature, August 22, p. 400), the third paragraph should read 

 as follows : — " The theory gives for the thickness {h) of ice 

 formed in the time (/) the following formula, which is approxi- 

 mately correct — 



ifU-,^f -) = ''''. 



In this formula {c) is the specific and (\) the latent heat of ice ; 

 {k) is the coefficient of conduction, {a) is specific gravity, (/) is 

 the temperature at the surface of the ice at the time i^t), (T) 

 the sum of cold for the same time ; the last is the sum of the 

 temperatures counted downwards from 28" F., or the freezing- 

 point of sea- water, from the commencement of ice forjiation up 

 to the time (/)." 



The additions to the Zoological Society's Gardens during the 

 past week include a Common Peafowl {Pavo cristalus i , white 

 variety) from India, presented by Mr. Richard Hunter ; a Manx 

 Shearwater {ruffiniis anglorum) from Essex, presented by Mr. 

 J. M. Wood, C.E. ; a Lesser Razor-billed Curassow {Milua 

 tomcntosa) from Guiana, presented by Mr. G. H. Hawtayne, 

 CM Z.S. ; a Louisianian Meadow Starling [Slttmella ludo- 

 viciana 9 ) from North America, presented by Mr. Newton 

 Hayley ; a Turtle Dove {Jurtur communis), European, pre- 

 sented by Mr. C. W. Cousins ; five Herring Gulls {Larus 

 argentati'.s), British, presented by Sir Richard Nicholson. 



