June 1, 1887.] 



KNOWLEDGE ♦ 



189 



Serious illness in his family, and resulting anxieties 

 and lossas, prevent the Editor from devoting so much atten- 

 tion as usual to " Gossip " this month. For a like reason 

 no new puzzles are given, as the Editor has not had time to 

 de\Tse any which seemed suitable. Hereafter" Mathematical 

 Recreations " will take the place of the Puzzles. 



The undersigned feels sure that INIr. Proctor's many 

 friends ■will be grieved to hear that a deep shadow has fallen 

 on the home which he has temporarily pitched in America 

 in the loss of two children, one of them a bright and charm- 

 ing boy of five years, through that terrible .slayer of the 

 Innocents — scarlet fever. These columns offer a convenient 

 place for our e.xpression of sympathy with Mr. and IMrs. 

 Proctor and their family. Edw.^rd Ci.odd. 



Overwork and Premat}i.rf: Mental Decay : its Treatment. 

 By C. H. F. PvOUTH, M.D. Fourth Edition. (London: 

 Baillit-re, Tindall & Cox. 1886.)— Reading through Dr. 

 Routh's eminently plain, sensible, and practical essay, we do 

 not wonder that it has already reached its fourth edition. In 

 our existing condition of incessant toil after wealth, position, 

 and pleasure, with men and women essaying to accomplish 

 three or four times the amount of work done by their grand- 

 fathers and grandmothers in the same time ; with our extra- 

 ordinary facilities for rapid locomotion, and with our purely 

 artificial condition of existence, what wonder if the over- 

 wrought machine gives way, and the originallj' strong man 

 becomes the veriest wreck of his former self \ How and 

 why this result supervenes, and under what treatment its 

 victim may be restored, Dr. Routh here tells us, and his 

 little book may be commended a.s a thoi'oughly trustworthy 

 guide to all upon whom worry and care are in any degree 

 beginning to tell. 



Alexanders Empire. By J. P. Mahaffv, D.D., with 

 the collaboration of Arthur Gillman, M.A. (London : 

 T. Fisher Unwin. 1887.) — Nothing probably is more 

 familiar to the student of history than the story of the suc- 

 cession of victories by which the mighty Macedonian 

 subjugated so large a proportion of the then known world ; 

 but the manner in which the different parts of his dominion 

 waxed and waned until they were finally swallowed up in 

 that edax rernm the Roman Empire, is by no means so well 

 known. It is, then, to the elucidation of this that the 

 narrative of Professor ilahafly is addressed. By far the 

 most interesting part of his work is that in which he traces 

 the influence of Hellenism on the conquered peoples, and 

 ■shows to what an extent it dominated the ideas of Rome 

 itself. In this connection chapters xiv., xx., and xxxii. may 

 be singled out as well worth}' of study. With reference to 

 the chronicles of the numerous wars into which the members 

 of the once consolidated empire plunged, we fear that they 

 will require more sustained attention than the larger pro- 

 portion of readers will be either able or willing to bestow. 

 In fiict, so confusing are the iterations and reiterations of 

 certain names, that Doctor Mahaffy thoughtfully concludes 

 with a " List of Names easily confounded." The illustra- 

 tions, of which there are no le.ss than forty-four, are one and 

 all apposite, and show the perfection to which Greek art 

 attained in architecture, sculpture, and numismatics. 



The Deviation of the Compass in Iron iildps. By W. H. 

 RossER. Second edition. (London : Jas. Imi-ay i Son. 

 1887.) — It has been known certainly ever since the twelfth 

 century that a magnetic needle, so balanced as to play hori- 



zontally about its pivot, points more or less approximately 

 to the north according to the part of the world in which the 

 observation is made. In fact, the Chinese claim to have 

 employed it in navigation from a period of the hoariest 

 antiquity. Now, as long as the directive force actuating 

 the needle resides solely in the earth itself, the jjhenomena 

 exhibited are sufficiently simple, and the compass is a com- 

 paratively trustworthy instrument ; and as this condition of 

 things obtained in efl'ect as long as .ships were built of wood 

 alone, the compass has foi' centuries been an aid of priceless 

 value to the navigator. But with the substitution of iron 

 and steel for wood in shipbuilding a total change has taken 

 place in the circumstances under which the compass is 

 employed ; for every iron ship that is built becomes herself 

 a gigantic magnet, with the direction of its polarity de- 

 pendent upon the position which the vessel occupied with 

 reference to the magnetic meridian during the time she was 

 being built, with the result that the most remarkable devia- 

 tions are found in the infinitely less powerful magnets of 

 the compasses on board. In Mr. Rosser's excellent work the 

 methods of ascertaining the exact amount of deviation of 

 the compass on board of an iron ship, both on an even keel 

 and when heeling to any extent, of the mechanical methods 

 of correcting such deviation, and of the tabulation of residual 

 errors at all azimuths, are lucidlj' laid down and explained 

 in language which must be intelligible to ever}' one com- 

 petent to navigate a vessel at all. Whether for sea use, for 

 the Board of Trade examination, or for the professional 

 compass-adjuster, no more useful or intelligible book than 

 the one before us has, so far, been published. 



Shoring and Its Application. By Geo. H. Blagrove. 

 (London : Crosby Lockwood & Co. 1887.) — -Here is an- 

 other excellent and thoroughly practical volume on a sub- 

 ject, the importance of which in connection with public 

 safety can hardly be over-estimated. Within the compass 

 of eighty-nine pages, ]\Ir. Blagrove deals with the whole art 

 of shoring, from its simple application in preventing the fall 

 of old and decaying walls and partly destroyed houses, up 

 to the complicated devices for the support of such structures 

 as St. Alban's Abbey and Beverley Minster. Our author 

 has made a distinct and valuable addition to the literature 

 of the building art. 



Messrs. Longmans send us an excellent Geographical 

 /.Vf A )■ adapted for the Seventii Standard ; and we have also 

 to acknowledge the current number of their magazine, of 

 which " Allan Quatermain " is the attractive feature ; also 

 of the American Naturalist, in which the valuable papers ou 

 the " Significance of Sex " are completed. 



<!B\\v WBWt Column. 



By " Five of Clubs." 



HE following game was played recently at Mel- 

 bourne. Tl^e wbist editor of the Australasian 

 played hand Y. The point of the game lies in 

 the play by I" of a small diamond at trick 2. It 

 will be seen by his notes that 1' considers the 

 play, though unusual, to have been justified by 

 the position. I cannot but think he risked the 

 loss of the game by passing. Tbia opinion is not 

 based solely on the error in calculating chances 

 into which Y fell, as his notes show. That error, by the way, is 

 very natural. It was made bj' the well-known mathematician, 

 D'Alembert (when, however, the mathematics of chance problems 

 was as yet in its infancy), in dealing with the toss of a coin. There 

 are three events, he said : two heads, two tails, and one of each ; 

 therefore the odds are two to one against the last. They are in 

 reality even, because one of each may occur in two ways — head 

 tail or tail head. 



