April ^, 1888] 



NATURE 



535 



Transactions of the Sanitary Institute of Gi-eat Britain. 

 York Congress, 1886. 



The valuable work done by the Sanitary Institute cannot 

 be altogether gauged by the annual volumes of Trans- 

 actions, one of which now lies before us. It must be 

 remembered that, besides the reading of papers and hold- 

 ing of discussions on subjects of sanitary interest, the 

 Sanitary Institute endeavoui-s, by means of its Congresses 

 and annual Exhibitions, to arouse the interest of the 

 inhabitants no less than of Town Councils and municipal 

 authorities in the health and well-being of the towns 

 visited. That such visitations have a beneficial influence, 

 by awakening public interest in measures of sanitary 

 reform, both local and general, can hardly be doubted ; 

 and, as pointed out by Sir Spencer Wells in his Pre- 

 sidential Address, if further legislation on sanitary matters 

 is not to be ridiculous, it must be accompanied by increased 

 knowledge on the part both of the persons charged with 

 administering the Sanitary Acts as well as of the public 

 themselves. 



The modern science of hygiene is hybrid, embracing as 

 it does special brandies of most of the leading sciences — 

 medicine, engineering, architecture, geology, chemistry, 

 meteorology, &c. The subjects treated of by means of 

 papers in such a Congress must be very varied, and such 

 we find to be the case ; but as far as possible the papers 

 are relegated to one of three sections, where their merits 

 will be best understood and most adequately discussed. 

 The standard of the papers submitted to the York Con- 

 gress is fully up to the average, many of them treating of 

 subjects of wide interest, or having important bearings on 

 the prevention of disease and maintenance of the public 

 health. 



Science SketcJies. By David Starr Jordan. (Chicago : 

 A. C. McClurg and Co., 1888.) 



In this neat and handy little volume we have a very 

 interesting and intellectual collection of sketches and 

 addresses more or less scientific. Some of the articles, 

 which, as the author tells us, have been published before, 

 have been freely retouched or re-written ; but the papers 

 on "The Dispersion of Fresh-water Fishes," " The Evolu- 

 tion of the College Curriculum," and the address on 

 " Darwin " appear for the first time. The subjects treated 

 are of various kinds, so that anyone who takes up the 

 book will be sure to find in it something that will interest 

 him. The appendix contains a list of the scientific papers 

 of the author, and ,we hope it will not be long before we 

 are favoured with another such book as the above. 



LETTERS TO THE EDITOR. 



\The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

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

 rejected manuscripts intended for this or any other part 

 (t/" Nature. No notice is taken of anonymous communi- 

 cations. '\ 



"Coral Formations." 



Since writingtheletterpublishedin NATURE,March22(p.488) 

 I have checked Mr. Ross's figures. The result is somewhat 

 surprising. Instead of 8400 tons of carbonate of lime removed 

 from 12!^ square miles of lagoon representing a sheet half an 

 inch thick, it really only amounts to a film of that area ^J-tj- of 

 an inch thick. 



At this rate per annum it would in round figures take eighteen 

 thousand years to dissolve out a lagoon a fathom deep, or a 

 million years for the creation of a lagoon 60 fathoms deep. 

 When we consider that this could only happen on the impossible 

 assumption of the atoll remaining stationary for a million years, 

 while no accumulation of coral sediment or organic calcareous 

 growth took place in the lagoon, it is at once seen, on the showing 

 of its own supporters, how impotent is the solution theory to 

 account for the formation of lagoons in atolls. 



To represent the figures in a familiar way, I may point out 

 that the film removed annually would be a little less in thickness 

 than one of the pages of " Prestwich's Geology." A volume 

 of 36,000 pages (18,000 leaves), minus covers and well pressed, 

 would be a fathom thick. No one acquainted with my geo- 

 logical work will accuse me of being parsimonious of geological 

 time, but this is really beyond my mark altogether. 



Mr. Irvine asks (Nature, March 29, p. 509) : " Can Mr. 

 Reade give any observations or figures in support of his view of 

 the rate of accumulation of oceanic calcareous deposits ? " 



If Mr. Irvine will refer to Mr. Murray's paper (Nature, 

 vol. xxii. p. 352), he will see that the pelagic life in a square 

 mile of ocean water 100 fathoms deep is estimated by him to 

 represent sixteen tons of carbonate of lime. 



I am not aware of the length of life of such organisms, but if 

 they lived on an average only one day, and the whole of their 

 tests were rained down on to a submarine peak at the rate of 

 sixteen tons per diem, and none were dissolved by sea-wafer, it 

 would take twenty-nine years to accumulate I inch in thickness 

 of solid carbonate of lime in this pelagic cemetery. In this way, 

 if anything so improbable were to happen, a submarine peak 

 half a mile below the range of coral growth might be levelled 

 up into a suitable platform in 900,000 years. I could add much 

 more, but respect for your valuable space bids me conclude. 



T. Mellard Reade. 



Park Corner, Blundellsands, April 3. 



"The Dispersion of Seeds and Plants." 



In support of the views expressed in Mr. D. Morris's interesting 

 article on the above subject (Nature, March 15, p. 466), I 

 beg to be allowed to state the following facts. In the Island 

 of Porto Rico, \ht Panic urn barbinode, called there " malojilla," 

 has been cultivated for many years in the low humid lands, and 

 it is a current opinion among farmers that it is reproduced by 

 means of the animals feeding on it. Some fruit-bearing trees 

 and shrubs, which are a favourite food for the wild Columba 

 leucocephala and Columba corensis — among them the Solanum 

 stramonifolium, the Bucida Buceras, the wild coffee, Coffea 

 occidentalis, the palm-tree, Oredoxa regia — appear in some 

 mountains and regions where they were formerly unknown, and 

 there is no doubt that they have sprung from fruits and seeds 

 transported by these pigeons. The Anona muricata (soursop), 

 the Anona reticulata (custard apple), the Carica papaya (papaw 

 tree), whose hard seeds are sometimes uninjured by the processes 

 of mastication and digestion, are also believed to be planted 

 accidentally by birds, and sometimes by hogs, hors:s, and other 

 Mammalia. They grow all about in pastures where these 

 animals are fed. The statement made about the orange-tree 

 in Jamaica also holds good for Porto Rico. Very few orange- 

 trees were planted in the interior of the country, and the tree is 

 now wild in all that zone by the agency of birds in great part. 

 There is no doubt, as Mr. Morris says, that birds and cattle have 

 been the means of distributing plants all over the island. 



Antonio J. Amadeo. 



'•Balbin's Quaternions." 



Nature of December 15, i887(p. 145), which has lately reached 

 me, contains a notice of a treatise on Quaternions, by Prof. 

 Valentin Balbin, in which the reviewer alludes to the "slight 

 alterations " introduced into the notation of quaternions by 

 Messrs. Houel and Laisant, and apparently visits them all with 

 equal condemnation. 



To me it appears that a distinction should be made between 

 the two points in which the French notation differs from the 

 English. The use of letters in different type to denote different 

 kinds of quantities, the same type being always reserved for the 

 same kind, seems to render the processes sometimes clearer and 

 the results more immediately and easily available for students. 

 In spite, therefore, of the ugliness of the black-letter symbols, 

 it would not perhaps be altogether a loss if English mathe- 

 maticians would adopt this part of the French scheme. 



The other change introduced by M. Houel, that of the order 

 of the factors, writing (j c/ where Hamilton writes / </, seems, 

 on the contrary, to be an entirely retrograde step. That, as a 

 rule, the symbol for the operator should be written before that 

 of the operand, is a necessity in all modern symbolic processes. 

 The alteration can only lead to confusion. In my " Text-book 

 of Algebra" I have suggested that while the symbol a x b 



