482 



NATURE 



[Sept. 22, 1887 



"for students of all denominations who can command 

 the means and have the wish to construct for themselves 

 a histological cabinet," and that it has been produced 

 " between the numerous and unavoidable interruptions of 

 a family medical practice." G. B. H. 



OUR BOOK SHELF. 



Precious Stones in Nature, Art, and Literature. By S. 

 M. Burnham. (Boston : Bradlee Whidden. London : 

 Triibner and Co.) 



Mr. Burnham is the author of a work on limestones 

 and marbles published a few years ago in which he in- 

 dicated the resources of the United States and other 

 countries in stone for decorative purposes. In the present 

 volume he treats of precious stones in that exhaustive and 

 thorough fashion which we are accustomed to regard as a 

 special characteristic of German writers. He begins by 

 describing, as far as is known, the origin, properties, 

 classification, localities, imitations, and antiquity, of 

 precious stones (antiquity here applies of course to their 

 use as ornaments), and then proceeds to treat of their 

 prices, the trade in them, the sumptuary laws relating to 

 them, those of remarkable size, and notorious jewel rob- 

 beries. This chapter is followed by a description of various 

 notable collections, and of the Crown jewels of different 

 countries, from which the author passes on to some very 

 interesting chapters on the secular uses of precious stones, 

 the different kinds of ornaments, and their sacred uses. A 

 chapter on precious stones in literature, and their mystical 

 properties, is succeeded by one on the curious art of en- 

 graving on precious stones, and then commences a series 

 of chapters on the various stones. First, of course, comes 

 an account of the diamond, its home, and of historical and 

 remarkable diamonds, which is followed by descriptions 

 of all the precious stones at present known, from the 

 sapphire, emerald, and ruby, to coral, amber, jet, cat's-eye, 

 and rock-crystal, to the number of about one hundred. 

 The appendices give the sizes of large and remarkable dia- 

 monds, a classification of precious stones according to their 

 principal constituents, the hardness and specific gravity 

 of precious stones, their relative hardness, relative specific 

 gravity, and finally a list of the localities in the United 

 States in which gem-minerals have been found. It will 

 be perceived from this very brief indication of the'contents 

 of the book that the work is perfectly encyclopaedic in its 

 treatment of its subject ; nothing relating to precious 

 stones is strange to or disregarded by Mr. Burnham. Of 

 the value of the book to the gem collector, expert, or miner- 

 alogist, it is needless to speak, but we can answer for it 

 that it is highly interesting to the general reader, or at 

 least to all who like to hear about those rare and beautiful 

 products of Nature to which man in all ages and in every 

 country has attached a high value. 



Hydrophobia : An Account of M. Pasteur'' s System. By 

 Renaud Suzor. (London: Chatto and Windus, 1887.) 



Dr. Renaud Suzor is the delegate commissioned by 

 the Government of the colony of Mauritius to come to 

 Europe to study M. Pasteur's treatment of hydrophobia, 

 and this volume is the result of his mission. It is 

 greatly to the credit of Sir John Pope Hennessy, the 

 Governor of that colony, and of the members of the 

 Legislative Council, that they perceived the value to 

 science and humanity of adequately studying M. Pasteur's 

 recent discoveries on the subject of hydrophobia, and 

 that they "unanimously voted" the appointment of a 

 delegate to proceed to Paris to work under the distin- 

 guished discoverer. It is to be hoped that other and more 

 prominent colonies may be led to follow this excellent 

 example. This little volume amply justifies the selection 

 of Dr. Suzor as delegate. It opens with an historical 



account of hydrophobia and its treatment from the earliest 

 times— for this dreadful disease has been known and 

 studied for more than 2000 years — down to the end of 

 1880. The second and principal part of the volume is 

 occupied by translations of all M. Pasteur's communica- 

 tions on the subject to the Academy of Sciences, beginning 

 with his first note in January 1881, and ending with a 

 lengthy paper presented in November 1886. Finally, 

 there is a description of the technique of M. Pasteur's 

 method. The book is valuable as a clear and compara- 

 tively untechnical exposition of the Pasteur method ; but 

 it is still more valuable as an example of the manner in 

 which Pasteur's wonderful discovery should be met and 

 treated by Governments and others in authority, who are 

 responsible for the prevention, as far as possible, of 

 disease amongst the populations which they govern. The 

 Governor of Mauritius has taken care that the neglect of 

 this primary duty, in relation at least to hydrophobia, 

 cannot be laid to his charge. 



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 ivith the writers of, 

 rejected manuscripts. No notice is taken of anonymous 

 com m un ic at ions. 



[ The Editor urgently requests correspondents to keep their 

 letters as short as possible. The pressure on his spcue 

 is so- great that it is impossible otherwise to insure the 

 appearance even of com/iiunications containing interesting 

 and novel facts. "] 



A Monstrous Foxglove. 



A SOLITARY specimen of Digitalis purpurea was found last 

 month in a damp wood near Old Colwyn, North Wales, which 

 exhibited the following curious abnormalities in the structure of 

 its flowers. In only one out of the six opened flowers of the 

 raceme was the calyx normal {i.e. consisting of four broad and 

 one narrow segment) ; in all the others it was divided almost 

 to the base into five equal linear segments. The corolla in four 

 out of the six flowers consisted of merely two narrow petals with 

 long claws, placed at opposite points .on the receptacle ; in one 

 flower these two distinct floral leaves were deeply divided into 

 t«o and three lobes respectively, thus forming a perfect two- 

 lipped flower, the lips, however, being quite separate from 

 one another. In the only other flower the upper lip was alto- 

 gether wanting, the three-lobed lower one alone being present, 

 upon which, alternating with its lobes, were inserted one long 

 and one short stamen. This was the only flower which possessed 

 stamens. 



The form and number of the styles also was variable and 

 abnormal. In one flower only was the usual single shortly two- 

 cleft style met with ; two other flowers possessed each a single 

 style forked below the middle ; in two others there were two, 

 and in the remaining flower three styles, all separate and 

 similar. 



The same abnormalities were seen in the corolla and styles of 

 two unopened buds. 



I should be happy to learn if such monstrous forms are at all 

 usual in the foxglove. F. R. Tennant. 



Longport, Staff. 



The Law of Error. 



Dr. Venn, in a letter published in Nature, September t 

 (p. 411), adduces certain meteorological statistics which do not 

 conform to the typical law of error or probability-curve. To 

 discover the cause of this failure there would be required both 

 a special knowledge of the subject-matter and the general con- 

 ceptions which the calculus of probabilities supplies. The latter 

 qualification is the only one to which the present writer can make^ 

 any pretension. 



The essential condition of the typical law being fulfilled 

 that each observation or statistical return should be made up 

 of a great number of independent variable items. A good ex- 

 ample is afforded by taking a great number, e.g. 100, digits at 

 random from mathematical tables. The sums of that number 



