144 



NATURE 



\_ynnc I 7, iSSo 



other times his language is rather singular, as when he 

 says that stammering "frequently arises from a mus- 

 cular defect, giving rise to a clumsiness in getUno the 

 ions:ue round one or mo'e letters" (p. 94), or speaks of 

 the vocal bands being "tensed" (p. 105), or says that 

 "musical gifts of voice are rather phylogenetic in their 

 origin," the word in italics not appearing even in Mayne, or 

 speaks of " living up hills" (p. 146). In a book Avritten for 

 singers and public speakers Latin and Greek and technical 

 expressions should certainly be explained, if not avoided, 

 such as phylogenetic, already adduced, and frccnum 

 Ungues (p. 95). The article on hygiene conveys a good 

 deal of information, but we suspect most readers will 

 rather remember the amusing account of the dietetic 

 habits of singers, c[uoted from other sources, on p. 114, 

 than be able to dig out what relates to the voice from the 

 great mass of other matter. In conclusion, we cannot 

 help feeling that the words "the science of," in the 

 title, are not justified by the book itself, and might be 

 advantageously replaced by the single word "on." 



Ceylon Coffee Soils and Manwes : a Report to the 

 Ceylon Coffee Planters' Association, By John Hughes. 

 (London : Straker Bros, and Co., 1879.) 

 The writer of this report has at least gathered together 

 a large amount of useful information about the coffee 

 plant, coffee soils, and coftee manures. As an agricultural 

 chemist he has, not unnaturally, attributed excessive 

 importance to the composition and condition of the soils 

 in which healthy and diseased coffee tree 5 are found ; 

 manures also are indicated as amongst the chief remedial 

 measures. Doubtless, the proper maintenance of the 

 "condition," as it is technically termed, of coffee soils 

 has been woefully neglected. Indeed, where there is 

 neither rotation nor even alternation of crops the difficulty 

 of securing continued vigour of growth and ample crops 

 of fruit must be considerable, even when soils are rich 

 and seasons favourable. But let any adverse influences, 

 whether of excessive rainfall, or of mechanical and 

 chemical injury to the soil occur, and then the plant is 

 more likely to succumb to the attacks of its enemies, 

 vegetable and animal. Thus wheat straw deprived of 

 adequate supplies of soluble silica becomes more subject 

 to injury from insects and mildew. Other examples 

 might be found of a connection between certain de- 

 ficiencies in the soil and certain diseases in the plant, but 

 it is unsafe to make a hasty generalisation on this point. 

 In combating the coffee-leaf disease we must first of all 

 devote ourselves to the fungus which is its direct cause. 

 There can be little doubt that calcium sulphide, which 

 proved so efficient a means of destroying the Oidium of 

 the vine will be equally destructive to the Hemileia 

 ■vastatrix. A mixture of sulphur and quicklime, or a 

 wash made by simply boiling these two materials together, 

 is much less active. 



\Mien Mr. Hughes makes suggestions about the sources 

 of manurial substances available for Ceylon, about the 

 making and preser\-ation of cattle and vegetable manure, 

 and about terracing and draining, we can heartily endorse 

 his recommendations. And when he gives us a number 

 of careful anal} ses, some of which are of considerable 

 interest, even apart from their connection with the growth 

 of coffee, we are grateful for information which is sure to 

 become useful under some circumstances and at some 

 time. But there are certain portions of Mr. Hughes's 

 Report which seem to have been introduced with no 

 special object, or v.hich are of questionable value, ^\'e 

 hardly need to be taught that "Planters want a practical 

 remedy rather than an elaborate description of the 

 disease" (p. 140). The appearance of what look like 

 recommendations of the manurial preparations of par- 

 ticular manufacturers should have been avoided (pp. 27 

 to 30). We could have spared the repetition of the well- 

 Tvorn table of manurial values on p. 100, and the analysis 



of Bude sand (p. 36). The term. g?-anitic as applied (p. 37) 

 to a limestone containing over 70 per cent, of calcium 

 and magnesium carbonates needs a word of explanation. 

 Of really interesting data furnished by Mr. Hughes we 

 may cite the analyses of castor-seed cakes (p. 15), in 

 which the nitrogen is shown to differ widely — brown and 

 black cakes containing but 4^ per cent., while white cakes 

 show no less than 7i. Although we do not believe in the 

 third decimal places (how often can we chemists secure 

 accuracy in the tenths?) in iMr. Hughes's soil analyses 

 (pp. 46, 53, 65, 72, 77, Si, 150) — particularly as his phos- 

 phoric acid determinations were not madeby themolybdic 

 acid process — yet these results represent a mass of 

 laborious researches, and ought to furnish much material 

 for the management of Ceylon coffee soils. The analyses 

 of healthy and diseased coft'ee-leaves (pp. 142-144) deserve 

 careful study ; they point unmistakably to the fungoid 

 origin of the disease. A. H. C. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by his correspondints. Neither ean he undertake to return, or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken of anonymous communications. 



[ The 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 the appearance even of eom- 

 tnunieatio/ts containing interesting and novel facts.'] 



Cloud Classification 



Between M. Poey and his latest critic (Nature, vol. xxii. 

 p. 96) it would be impertinent for me to interfere. But until my 

 objection to a part of Howard's original classification has met with 

 some response from those who maintain the adequacy of that 

 classification I must continue, at the risk of some repetition, to 

 call attention to this objection. It can be stated briefly, and 

 I do not see why the answer thereto, if such exist, should be 

 deferred as too long for discussion. 



E. H. appears to admit that an observer, when within 

 a cloud (which is then to him a fog), cannot distinguish 

 cumulus from stratus. He, however, elevates the stratus, 

 or rather one variety of it, "a few feet (or even inches) 

 from the earth," so as to cut "the taller trees in a horizontal 

 line, leaving their tops and bottoms free." He proposes to 

 shelve the question "whether it is desirable to use the term 

 ' stratus ' for clouds in a totally different sky region, which differ 

 both in their origin and then- nature from the true stratus" (i.e., 

 from the stratus of the sky-region of half-length elms in the 

 Thames basin). Now it is precisely this question which the 

 large and growing class of observers, who wish to record the 

 modifications of clouds, can no longer permit to be left unsettled. 

 If clouds are to be classified according to their form at all, some 

 name is absolutely required for a class of clouds \\hich is in all 

 latitudes common, and in the higher predominant. These are the 

 clouds to which the observers can neither give the title cumulus 

 nor the title cirrus, the clouds which are disposed in beds or 

 layers whose vertical thickness is small. AVhen in trifling amount 

 they arrange themselves in irregular disks or patches capable of 

 being occasionally mistaken for cumulus when in the zenith, but 

 elsewhere seen as streaks or threads transverse to the meridian. 

 When in large amount they cover a great portion or the w hole 

 of the sky with a shallow and nearly level canopy. In England, 

 putting together observations made at all hours of day and 

 night, clouds belonging to this class are recorded in about 60 

 per cent, of the observations. Of observations made at 2 p.m. 

 they occur in about 38 per cent. ; of observations made between 

 sunset and sunrise in upwards of 90 per cent. Of observations 

 made at all hours in the English Midlands from October, 

 1S79, to February, iSSo, inclusive, they were recorded in S3 

 per cent. To leave this class nameless is intolerable. To give 

 to them either of tlie compound titles cumulo-stratus and stralo- 

 cumulus is objectionable, because in form they do not resemble 

 cumulus at all (I might add that to a defender of Howard's 

 unamended system they also do not resemble stratus at all, 

 differing, as we are told, not only in elevation, bnt in "origin 

 and nature," both from ground-fog and middle-tree fog). A 

 similar objection lies against the application to these clouds of 



