August 13, i89'ij 



NATURE 



547 



impure for the purpose, the preparation of a cubic metre 

 of oxygen was undertaken. The gas was prepared by 

 electrolysis, conducted through purifying apparatus, and 

 compressed into a steel cyclinder of lo litres capacity, at 

 a pressure of loo atmospheres by the mercury com- 

 pressor. The gas in the cylinder appeared to contain 

 nearly 99 per cent, of oxygen. How many laboratories 

 exist in which such a thing could be performed ? 



As to low temperatures, in No. 6 we notice the measure- 

 ment of the capillary elevation of ether at - 102' in boiling 

 ethylene ; in Xo. 18, of the same magnitude for carbonic 

 acid and nitrous oxide at - 24 in boiling methylchloride. 

 Nos. 4, 16, 18 contain the description of a method for 

 purifying gases by condensation and fractional distillation 

 at low temperature, in a bath of ethylene or in solid 

 carbonic acid, the gases purified being carbonic acid, 

 methylchloride, nitrous oxide, and ethane. Finally, we 

 may note the measurement of the viscosity of methyl- 

 chloride at - 30' in cooled alcohol. 



The different investigations hitherto carried out may 

 be arranged under the following headings. 



I. Cryogenic department : condensation of methane, iso- 

 thermals of hydrogen at low temperatures, &c. (Nos. 14, 23.) 



II. Investigations regarding critical points and con- 

 densation of mixtures -and of pure substances. (Dr. 

 Kuenen. Nos. 4, 7, 8, 11, 13, 'i6, 17.) 



III. Measurements on the capillarity of ether, carbonic 

 acid, nitrous oxide, &c. (Drs. dc \'ries and Verschaffelt. 

 Nos. 6, 18.) 



I\'. Measurements on the \iscosity of methylchloride 

 in connection with the laws of corresponding states of 

 matter. (Drs. Stoel and de Haas. Nos. 2, 12.) 



\'. Series of experiments on Kerr's magneto-optical 

 phenomenon, &c. (Drs. Sissingh, Wind and Zeeman. 

 Nos. I, 3, 5, 8, 9, ID, 15, 20.) 



V'l. Some experiments regarding Hall's phenomenon 

 in bismuth. (Dr. Lebret. Nos. 15, 19.) 



VII. On Hertz-wa\es in water and in electrolytes. (Dr. 

 Zeeman, partly in conjunction with Prof. Cohn, Strass- 

 burg. Nos. 21, 22.) 



\'III. Observations on the dispersion of magnetic 

 rotation in gases. (Dr. Siertsema. Nos. 7, 15.) 



The scope of this article does not allow of a further 

 description or discussion of any of the above investiga- 

 tions. One instance will show the scale on which the 

 experiments are carried on, if deemed necessary. For 

 the observations mentioned under \'1 1 1., two coils were 

 constructed, each of i metre length and with 3600 turns of 

 6 mm. wire, the joint resistance of the coils in series 

 being i ohm, and the current carried 70 amperes. 



besides a dynamo there are two or three sets of 

 accumulators, which make it possible to work simul- 

 taneously at two or three investigations for which strong 

 currents and electric lamps are required. In short, the 

 place is rich in apparatus of all kinds, and possesses 

 numerous appliances ; so much so, that one would rank it 

 amongst the best pro\ided (and, one may add, most pro- 

 ducti\e) research laboratories. It is worth observing^ 

 that in Holland private munificence is hardly ever 

 directed towards scientific work, and that the whole 

 of this laboratory, as of all the others in the three 

 Government Universities — Leiden, Utrecht, Groningen — 

 are kept up from the public purse. It is only recently that, 

 under the strain of the competition between the Univer- 

 sities, private societies have been founded to promote 

 University work, where the Government shows itself 

 unwilling or unable to provide the necessary means. 



Those to whom these " Communications " are unknown, 

 and who are desirous of becoming more intimately 

 acquainted with their contents, have only to apply for 

 copies to receive them. I'rof. Onnes will, moreover, be 

 very glad if physicists, touring in Holland, would alight 

 at the famous University town, and in their programme 

 include a visit to his laboratory. 



NO. 1 398, VOL. 54J 



THE GREAT RIFT VALLEY> 



T T is but rarely that a narrative of travel, however 

 •'■ interesting it may be, and however exciting the 

 adventures of the author may have proved, has as much 

 attraction for naturalists and geologists as the present 

 volume possesses. Dr. Gregory has shown himself a 

 thoroughly competent explorer, for he succeeded in reach- 

 ing the glaciers close to the summit of Mount Kenya, 

 the highest peak of British East Africa, a task in which 

 several previous travellers had failed ; and he also- 

 examined a considerable length of the extraordinary 

 tract that gives its name to the book before us. This, 

 too, was accomplished with a much smaller caravan than 

 was regarded by experienced men as necessary for safety ; 

 in face of difficulties, due to the proclivities of the natives 

 and to scarcity of food, that would have daunted many 

 men ; in spite of the utter failure of the expedition to 

 which the author was originally attached ; and, above 

 all, despite severe attacks of malarial fe\-erand dysentery. 

 "The Great Rift Valley," apart from its scientific interest, 

 gives a very interesting account of an adventurous 

 exploit, carried out with courage and firmness, and, at 

 the same time, with kindly treatment of the natives 

 employed and encountered. 



It is, howe\'er, not as a record of exploration alone 

 that this book needs notice. Explorers equal to Dr. 

 Gregory in courage and tact, and perhaps superior to him 

 in the power of resisting malarial influences, have made 

 their way through many of the forests and deserts of 

 .\frica, and have told some of the secrets of the Dark 

 Continent to an appreciative audience ; but very few of 

 those who returned to tell the tale of their adventures 

 possessed the scientific training that gives an especial 

 value to Dr. (Gregory's account of his travels. In this 

 respect the author of the present work is singularly 

 qualified. In the era of specialisation in science that we 

 have now entered upon, it is becoming rare to find a 

 geologist who knows anything of zoology or botany, or a 

 zoologist or botanist who can tell schist from shale or 

 sandstone from granite ; whilst it appears to be rapidly 

 becoming a point almost of honour with the geologists, 

 zoologists, and botanists of the British Islands to regard 

 palaeontology as an inferior science. It is therefore 

 noteworthy that Dr. Gregory, who is a palaeontologist, 

 should have brought back from Eastern .'\frica a mass of 

 observations that could not have been accumulated by a 

 geologist ignorant of biology, nor by a zoologist or 

 botanist unacquainted with geology. 



Briefly the history of the journey described is this. 

 In November 1892, Dr. Gregory received leave of absence 

 from the Trustees of the British Museum to enable him 

 to join an expedition to Lake Rudolf From various, 

 causes this expedition was a failure. .After the dispersal 

 of its members. Dr. Gregory went on to Mombasa, where 

 he engaged a small party of porters, and in March 1893. 

 started ;for Lake .Baringo and Mount Kenya, and suc- 

 ceeded in reaching both. The journey occupied five 

 months, and the - expedition returned to Mombasa in 

 .August. 



The arrangement of the present work is the following. 

 .•\fter an introduction, giving a general account of pre- 

 vious exploration, and of the geology of the area as known 

 before the authors visit, the first three chapters relate his 

 experience with the abortive expedition which started 

 from Lamu to explore Lake Rudolf and the regions 

 between that lake and the Red Sea, but never got beyond 

 the lower reaches of the Tana River ; then eight chapters 

 contain a description of the journey to Baringo and 

 Kenya ; and the third part of the book, comprising- 



1 " The Gre.-it Rift V.-illey : being the N.irrative of a Jouiney to Mount 

 Kenya and Lake Baringo, with some Account of the Geology, Natural 

 Hi<;tory, .Anthropology, and Future Prospects of British East Africa." By 

 J W Gregory, D.Sc , F.G.S.. F.R.G.S., F.Z.S., of the British Museum 

 (Natur.-il History). (London : John Murray, 189S.) 



