228 



NA TURE 



[January 8, 1903 



and the subject is sufficiently clothed and fed, he will 

 probably be able to accomplish a very much larger amount 

 of mental work, without being over-strained, than would 

 be the case if these conditions were neglected. 



In Germany, the question of dealing with over brain 

 work is probably more pressing than it is in this country, 

 because the brain is often over-exercised, while there is 

 an insufficiency of physical exercise. In England, I am 

 afraid, it is more often a question of physical fatigue 

 than one of mental strain with which we are faced. But 

 of course, when the teaching system is "unintelligent" — 

 that is, one of cram — the poor brain must get terribly 

 wearied. 



Mr. Sadler has compiled the report with great care, 

 and the portions which he has himself written are marked 

 by a refreshing breadth of view not always to be found 

 in Government reports. It is probable, however, that 

 the object would be better attained if these reports were 

 more condensed. F. Mollwo Perkin. 



TIDAL CURRENTS IN THE GULF OF ST. 

 LA WRENCE. 



FOR many years past, the Canadian Government has 

 been prosecuting an accurate survey of the com- 

 plicated tides and tidal currents of the Gulf of St. 

 Lawrence. The Tidal Department, under the able 

 directorship of Mr. W. Bell Dawson, has already done 

 much excellent work in this field, although, doubtless, 

 much yet remains to be discovered. In the tidal report 

 for the present year, Mr. Dawson will describe the 

 results of a careful analysis of the remarkable tidal 

 currents which are met with in Northumberland Strait 

 south of Prince Edward's Island. At most places, the 

 times of the changes of tidal currents bear a more or 

 less constant relationship to the times of high and low 

 water, but in this channel the changes are found to be 

 largely governed by the moon's declination. As Mr. 

 Dawson remarks: — "This is very confusing to the 

 mariner, as the turn of the current in relation to the 

 tide is out of accord with the moon's phases, and has 

 thus no fixed relation to the spring and neap tides. The 

 greatest apparent irregularity is when the moon's de- 

 clination is at its maximum ; and this occurs sometimes 

 at the spring tides and sometimes at the neaps. The 

 ordinary navigator takes refuge in the conclusion that 

 the currents are chiefly influenced by the wind." 



Diurnal tides are ruled by the declination of the 

 moon, and it would seem that there must be at this place 

 a large diurnal inequality which manifests itself more by 

 current than by variations of height. 



Those who are interested in this subject will do well 

 to refer to Mr. Dawson's forthcoming report. 



G. H. D. 



JOHANNES WISLICENUS. 



'THE generation that laid the foundation of organic 



*■ chemistry has almost become a thing of the past, 



and at the close of last year one of the few remaining 



links was broken by the death ol Wislicenus. 



Not long since, the University of Leipzig was mourning 

 the loss, at a venerable age, of a distinguished physicist ; 

 to-day the chair which was made famous by that " wahre 

 Bearbeiter" Kolbe is vacant, and a name which will ever 

 be illustrious in the history of spacial chemistry has been 

 added to the classical traditions of this great seat of 

 learning. 



The news has come not as a sudden shock, for of late 

 years the health of the venerable Geheimrath has been 

 visibly declining, and waning strength and feeble gait 

 warned his many friends that his working days would 

 soon be over ; none the less poignant, however, is the 



NO. 1732, VOL. 67] 



grief felt by all who have had the privilege of sharing 

 his friendship or coming under the influence of his 

 impressive and genial personality. 



Johannes Wislicenus was born on June 24, 1835, at 

 Klein-Eichsted, in the Prussian province of Saxony ; 

 when he was five years old, his father, a pastor, was 

 transferred to Halle a. Salle, and there the boy received 

 his first impressions of school life. At the " Frankesche 

 Stiflung,"a school which has since become celebrated, he 

 lemained until the age of eighteen, and at Easter, 1853, 

 having passed his Maturitatsexamen, he entered the 

 University of Halle with the intention of devoting himself 

 to the study of natural science. His project was, how- 

 ever, soon frustrated. The political horizon was still 

 clouded over, and in consequence of certain intrigues, 

 his father, in the autumn of the same year, was com- 

 pelled to fly the country ; he found a home for himself 

 and his family, as did so many refugees of that time, in 

 the United States. In the following year, Johannes was 

 appointed assistant to Prof. Horsford at Harvard Uni- 

 versity, Mass., and in 1855 became lecturer at the 

 Mechanics' Institute, New York, with a laboratory at his 

 disposal. 



It was thus that he acquired that command of English 

 which was such a source of wonder to his foreign 

 students in later years. 



In 1856, he was able to return to Europe, and resumed 

 his interrupted studies at the University of Zurich, where 

 he " promovierte" in 1S60 and was appointed Privat- 

 docent at the Polytechnic. 



In 1861, he became professor of chemistry and 

 mineralogy at the " Kuntonale Industrieschule." four 

 years later, he received the honour of a chair at the 

 University of Zurich, and in 187 1 was elected by the 

 "Bundesrath" as director of the Polytechnic in that 

 town. In the following year, he was chosen to succeed 

 Ad. Strecker at Wiirzburg. There he remained until 

 1885, and it was duting this time that he carried on his 

 classical researches on the constitution of acetoacetic 

 ether and so established his reputation on a firm basis. 



The year 1884 witnessed the death of Kolbe and the 

 call of Wislicenus to Leipzig, where he remained until 

 the end. As was pointed out by a writer recently in this 

 Journal, "there is a curious irony in the thought that his 

 first work there should have been directed towards the 

 extension of the theory of Van 't Hoff, whom Kolbe had 

 regarded with such contempt." 



Of his scientific workspace will only permit the barest 

 outline. His researches were confined almost exclusively 

 to the domain of organic chemistry, most of them appear- 

 ing in Liebiifs Annalen der Chemie. The constitution of 

 lactic acid, on which he worked from 1863 to 1872, 

 establishing the identity of structure for the two different 

 substances fermentation- and para-lactic acids, first 

 brought him into prominence among chemical workers 

 and impelled him to seek an explanation of the meta- 

 merism in the spacial relations of the atoms within the 

 molecule. His interest in acetoacetic ether, to which 

 reference has already been made, resulted in a detailed 

 investigation of its reactions and of its value as a 

 synthetic agent ; these have gone far to stimulate the 

 study of this most interesting compound, and are of 

 importance, if for no other reason, lor the light they 

 throw on the still open question of its constitution. 



It was in Leipzig, however, that he achieved his great 

 work. In 1887 appeared his famous memoir, " Uber die 

 raiimliche Anordnung der Atome in organischen Mole- 

 kulen," to account for the phenomena of " geometrical 

 isomerism." According to his hypothesis, which was 

 an extension of that formulated independently by Le Bel 

 and Van 't Hoff in 1874, ''the centre of gravity of a 

 carbon atom was regarded as situated in the centre of a 

 tetrahedron, and its four affinities at the four corners." 

 When two atoms were linked together, Van 't Hoff, and 



