Sept. 30, 1 880] 



NA TURE 



509 



appear as his co-inventors on the Plates illustrating 

 these different appliances. 



' The accuracy attained with Sigsbee's sounding-machine 

 is very great, the probable error of sounding with piano 

 wire at great depths not exceeding one quarter of one per 

 cent. What the error may be if soundings taken by the 

 old methods will only be known when all the former rope 

 soundings have been repeated with wire soundings. 



The last chapters are taken up with descriptions of the 

 double trawls, the dredges, and other apparatus for col- 

 lecting the animals found at great depths. An account is 

 also given of making a haul at great depth and of the 

 management of the steel wire rope, first introduced by 

 ]\Ir. Agassiz for deep-sea dredging on the Blake, and 

 which has done so much to facilitate this class of work on 

 vessels of the small tonnage of the Blake. 



The Report is fully illustrated with heliotype plates as 

 well as with tables showing the manner of recording the 

 observations made. 



It is pleasant to notice that the harmony between the 

 civilians and the officers was not for an instant disturbed, 

 during the three dredging cruises made by the Blake, 

 extending from the Windward Isles to the Eastern 

 extremity of George's Shoal. 



The naturahsts on board the Blake were indeed fortunate 

 to have as their associates officers whose industry, energy, 

 and interest in the work never flagged, and who have now 

 attained a proficiency in deep-sea work hardly deemed 

 possible three years ago. 



OUR BOOK SHELF 



i. Elements of the Differential Calculus, with Examples 

 and Applications : a Text- book. By W. E. Byerly, 

 Ph.D. (Boston: Ginn and Heath, 1S79.) 



ii. An Elementary Treatise on the Differential Calculus, 

 founded on the Method of Rates or Fluxions. By John 

 Minot Rice and W. Woolsey Johnson. Revised Edi- 

 tion. (New York : J.Wiley and Sons, 1879.) 



Nearly five years have passed since we noticed a small 

 pamphlet by the authors of (ii.), together with treatises 

 on the calculus of Messrs. Buckingham (Chicago) and 

 Clark (Cincinnati), and we then remarked upon the 

 growing interest taken in mathematics by American 

 students. A further outcome of the same interest is the 

 two works now before us. As it is not to be expected that 

 such works will take the place in our colleges of the text- 

 books already in use amongst English mathematicians, 

 seeing that, like our own books, these are greatly indebted 

 to the classic works by Duhanel and Bertrand, we 

 shall not dwell at any length upon their merits or demerits. 

 Each work under notice is well done to the extent to 

 which it goes, and will furnish the young student with a 

 good introduction to the admittedly difficult subject of 

 which it treats. 



(i.) takes as its foundation the " rigorous use of the 

 doctrine of limits," introducing easy integration at a 

 very early stage, and has frequent recourse to geometrical 

 and mechanical illustration with a view to making the 

 subject of interest. 



(ii.) is the elaboration, in an excellent work, of the 

 paper (subsequently a pamphlet) referred to above, which 

 was introduced to the notice of English readers by a 

 resume of its contents in the Messenger of Mathematics 

 (August, 1S74) by I\Ir. Glaisher. 



Both books are effectively got up, and (ii.) is exceedingly 

 well printed. 



Spirit-Gravities with Tables. By Thomas Stevenson, 



M.D., &c. (London: John Van Voorst, 1880.) 

 Dr. Stevenson has published a series of Tables in 

 which the specific gi'avity of alcohol from 100 to o'os per 

 cent, is given for each difference of o'o5 per cent. The 

 percentages of alcohol by weight and volume, and of 

 proof spirit are contained in the Tables. The specific 

 gravities are given to four places of decimals. The 

 Tables are founded on those of Gilpin and Drinkwater, 

 and for spirits of less specific gravity than o"825o — i.e. 

 containing more than Sg'os per cent, by weight of alcohol 

 — on that of Fownes. 



In an introduction the various Tables hitherto in use 

 are discussed ; and various useful data are noted. The 

 Tables are clearly printed, and will be of much service to 

 those who are required to analyse alcoholic liquids. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself 7-esponsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken of anonyynous communications.^ 



[ Tlie Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure tJie appearance even op com- 

 munications containing interesting and novel facts.^ 



Supposed New Island in the Azores 



A REPORT was current in the English and American news- 

 papers some weeks ago that a new island had made its appear- 

 ance among the Azores, similar in character to that which came 

 up near the extreme western end of St. Michael's in the early 

 part of the centm-y. As I had determined to spend my long 

 vacation among these islands, I was curious to witness a pheno- 

 menon so intere-ting and so rare as the birth of a new volcanic 

 island. I learn that the report has its foundation in the occur- 

 rence of a landslip on the north-east end of St. George. A large 

 portion (about 82 alqueiros in extent) of the land at Lapa, near 

 the village marked Topo on Vidal's Chart, launched itself bodily 

 into the sea — that is, in an almost unbroken mass, to a distance 

 of about 300 metres from the mainland. There were a number 

 of cattle grazing on the land at the time ; these apparently were 

 so little affected by the occurrence that v.hen found they were 

 feeding unconcernedly on "the new island," as if it had been 

 associated with their whole existence. A little survey of the spot 

 has been made, and the Director of the Public Works at Vellas, 

 the chief town of St. George, was kind enough to give me a map 

 of this, the most recent addition to— or perhaps one ought to say 

 subtraction from — the Azores. T. E. Thorpe 



Parthenogenesis in the Coleoptera 

 In the "concluding remarks" in his treatise on " Wahi'e 

 Parthenogenesis" (1S56), von Siebold says, "Es ist daher jetzt 

 Aufgabe der Entomologen, nach weiteren Beispielen von Parthe- 

 nogenesis in der Insektenwelt zu forschen" ; and on the last page 

 (237) of his "Beitrage zur Parthenogenesis," published fifteen 

 years later, he expresses the conviction that many facts relating 

 to this phenomenon are still to be discovered. The instances of 

 true parthenogenesis discussed or referred to in these two works 

 relate to insects of the orders Hymenoptera and Lepidopter.n, 

 and to some crustaceans. Including viviparous ngamogenesis, 

 however, as parthenogenetic, the orders Hemiptera and Diptera 

 also furnish examples of this mode of reproduction ; and for its 

 occurrence in at least one genus of the Trichoptera I have the 

 authority of Mr. R. McLachlan, F.R.S. The possibility of 

 parthenogenetic reproduction in the Coleoptera rests only, so far 

 as I am° aware— see "Comparative Enibryology," by F. M. 

 Balfour, vol. i. p. 64— on the single iustanco communicated by 

 me to this journal last year (Nature, vol. xx. p. 430), and this 

 being so, it seemed desirable to make sure of this point by further 

 research during the season now almost past. Accordingly I 

 have this year kept a considerable number of females of Gastro- 

 physa raphani, laying unimpregnated eggs, and \\\\\\ results 

 which have not only confirmed the previous experience, hut 

 much extended it, as I am at present in possession of a living 



