January 13, 1910] 



NA TURE 



507 



from time to time observations, of minor importance, 

 perhaps, regarded as isolated facts, but valuable if 

 brouj^lit together and studied in relation to those of 

 other observers in the neighbourhood. Not the least ser- 

 vice rendered by a volume such as this is that it offers 

 a definite place of record for many a fact which would 

 otherwise probably be lost. We have discussed at 

 some length the biological matters, which occupy 

 about four-fifths of the book. In addition, there is 

 a brief general sketch of the geology, in which, as an 

 instance of interrelation between geology and industry, 

 it may be noted that Woolwich .'\rsenal is said to owe 

 its establishment to the suitability of the local Thanet 

 sands for iron-moulding. Scientific industries and 

 archaeology are other interesting chapters, and there 

 is a concluding note on Woolwich as a centre for 

 photography. The geological section has a very 

 useful bibliography, arranged chronologically. The 

 book is well indexed. W. G. F. 



The Flora of the Dutch West Indian Islaiiis. Vol. I., 



St. Etistatius, Saba, and St. Martin. By J. Bol- 



dingh. Pp. xii + 321. (Leyden : late E. J. Brill, 



Ltd., 1909.) Ppice 10s. 

 Considering the comparative proximity of the West 

 Indies and the number of nationalities in possession, 

 there is a lack of systematic botanical information 

 in the shape of local floras, so that Mr. Boldingh 

 renders good service by the publication of his work 

 relating to three of the Dutch possessions. It is based 

 primarily on his own observations and collections, 

 together with the collections of his countrymen. Dr. 

 Suringar, Mrs. van Grol-Meyer, and Dr. Lionarons, 

 totalling in all about 5000 numbers. The systematic 

 enumeration comprises 806 species, of which 674 are 

 regarded as indigenous and 166 are confined to the 

 West Indies. The Leguminosse is the best represented 

 family, with sixty species ; the Gramineee, Composite, 

 Polypodiaceae, and Euphorbiaceae follow in the order 

 named. Panicuni, Polypodium, and Peperomia are 

 the larger genera. Ipomoea supplies nine species, of 

 which two are limited to the West Indies, and another 

 is recorded only for St. Eustatius. Two other endemic 

 species, Galactia nuninutlaria and Calyptranthes Bol- 

 din_s,hii, have only been collected on St. Martin. 



The author follows Eggers in the ecological divi- 

 sions, and distinguishes littoral, cultivated, dry shrubby 

 or Croton, and tree or Eriodendron types of vegeta- 

 tion. The dry shrubby and tree vegetations are well de- 

 veloped on St. Eustatius ; on Saba the cultivated regions 

 and certain ferns are notable ; St. Martin is charac- 

 terised bv the extent of the littoral and shrubby vege- 

 tations, while forests are scanty. Generally speaking, 

 the flora of St. Martin differs from that of the other 

 two islands, and contains a number of plants repre- 

 sented on islands lying to the north, while the propor- 

 tion stands the other way with regard to certain 

 plants recorded only from islands lying to the south. 

 The author has rounded off his information with 

 geological and meteorological notes, a list of vernacu- 

 lar names, chiefly English, and maps. The flora bears 

 out the general view that there is no striking differ- 

 ence between the plants of neighbouring islands in the 

 group. 



Weather Forecastim^ by Simple Methods. By F. S. 

 Granger. Pp. xii+121. (Nottingham: Henry B. 

 Saxton, 1909.) Price 2S. 6d. net. 

 The aim of the author is to provide the means for 

 a single observer "to answer the question ' When will 

 it rain? ' in a simple and intelligible manner " without 

 the aid of instruments except a barometer, this, hov/- 

 ever, being regarded as optional, and not necessary. 

 The methods recommended are based mainly on ob- 

 servations of the size, thickness, extent, height, colours, 

 and forms of clouds. Different aspects of cumulus, 

 NO. 2098, VOL. 82] 



cirrus, and stratus cloud are discussed in relation to 

 the weather to be subsequently expected, and isolated 

 examples taken from the author's observations at 

 Nottingham are quoted. 



As the result of a long series of observations by an 

 observer who is evidently interested in the subject, 

 the work may prove useful to local observers, but it 

 is doubtful to what extent some of the conclusions 

 arrived at can be considered general. Thus "visi- 

 bility " is regarded as a sign of good weather, because 

 this phenomenon occurs at Nottingham only during 

 light easterly breezes. In some districts, however, 

 visibility is frequently associated with winds from 

 some westerly point, and is commonly supposed to be 

 a prognostic of rain. 



Although Mr. Granger again tells us that meteor- 

 ology is not an exact but an observational science, 

 he says in the same breath that his book is not 

 written on exact and scientific lines. He has described 

 it well. His cloud classification is incomplete, and is 

 not that approved by international agreement. He 

 ascribes the formation of cumulus to an electrical 

 cause, and states that lurid red skies in the morning 

 or evening are due to refraction of light. After using 

 the word "gradient" several times he at length 

 defines it as "the slope between two isobars when 

 on one the barometer is one-tenth of an inch higher 

 than the other," and speaks of a gradient of 300 miles, 

 a gradient of 29'g, a shallow gradient, and a form of 

 gradients. There are many other statements which 

 ought to be modified in the light of recent researches. 

 For example, our knowledge of the conditions in the 

 free atmosphere is not as limited as the author sug- 

 gests, and surely calculation already enters into the 

 science of forecasting, and must continue to do so to 

 an increasing extent. 



The arrangement of the work, especially with regard 

 to marshalling the descriptions under some definite 

 plan and arranging them in chapters with appropriate 

 headings, leaves much to be desired. The present 

 arrangement is almost fortuitous. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertalie 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part 0/ Nature. 

 No notice is taken of anonymous communications.] 



The Invention of the Slide Rule. 

 I HAVE read with great interest the abstract of the 

 paper on the invention of the slide rule, by Prof. F. 

 Cajori, which appeared in Nature of December 30, 1909. 

 I agree with the author in thinking that the Rev. William 

 Oughtred was the first to suggest that calculations could 

 be made more accurately and rapidly by sliding the edges 

 of logarithmic scales together than by using compasses 

 — the method adopted by Gunter ; but Oughtred had 

 a poor opinion of this device, and rightly considered that 

 his circular scale was a great improvement on it. A few 

 years before 1671, Seth Partridge' re-discovered the sliding 

 principle, perfected it, and gave an almost complete specifi- 

 cation for the slide rule which is used to-day by engineers. 



I was fortunate enough recently to come across, in the 

 library of the British Museum, a pamphlet written by 

 Oughtred in reply to an attack make on him by an instru- 

 ment maker called Delamain. The pamphlet is entitled 

 " To the English Gentrie and all other studious of the 

 Mathematicks, which shall be readers hereof. The just 

 apologie of Wil : Oughtred against the slanderous insimu- 

 lations of Richard Delamain, in a pamphlet called 

 Grammelogia, or the Mathematicall Ring." The author 

 very forcibly and very successfully rebuts the chargesthat 

 were made against him. The following gives his opinion 

 on the question of the priority of the discovery of the 

 circles of proportion : — 



1 "The Pescripti'in and LT^sc of an Instrument called the Double Scale of 

 Proportion," (London, 1671.) 



