254 



NA TURE 



[July 14, 1904 



devoting itself to the training of teachers and in- 

 structing them properly in the whole question of hygiene. 

 He trusted that as time went on its efforts in that direction 

 would bring about the desired results. 



In forwarding to Sir C. Eliot the meteorological returns 

 from fourteen stations in British East Africa, for 1903, Dr. 

 Johnson gives some particulars about the rainfall, and 

 these have been forwarded to us by the secretary of the 

 Meteorological Office. The average amount of rain did 

 not fall in the coast region during the period covered by 

 the report, only 33-84 inches being recorded at Mombasa, 

 23.24 inches at Malindi, 35.18 inches at Rabai, and 

 Takaungu received 33.72 inches. Shimoni fared better in 

 this respect, as 42.51 inches fell at that station. At up 

 country districts the amount of rain was well up to the 

 average; 80 inches fell at Mumias, 60 at Kisumu, and 

 51 at Fort Hall. The number of rainy days, i.e. days 

 on which at least o.oi inch of rain fell, varied from 23 

 at Kismayu to 174 at Eldoma ; and at Machakos the 

 number was 93; at Fort Hall, no; at Nairobi, in; at 

 Kisumu, 127; and at Mumias, 145. The greatest amount 

 of rain which fell in one day was 5.61 inches at Machakos, 

 on April 28, and the ne.\t heaviest rainfall was 4.77 inches 

 at Nairobi, on April 27. The Egyptian Survey Department 

 having asked for returns relating to the lake levels, and 

 also for returns of rainfall from places where the amount 

 of water in the lake would be affected by the amount of 

 rainfall, Dr. Johnson has forwarded instruments to the 

 stations in question, viz. : — Nandi, Kericho, and Karungu. 

 A supply of instruments has also been sent to Morendat 

 and to Nairobi, and it is hoped shortly to supplement those 

 already at Fort Hall. 



In Symons's Meteorological Magazine for June there is 

 a description of a new pattern rain gauge by Messrs. 

 Lander and Smith, of Canterbury, a firm of chemists which 

 has also recently produced some ingenious self-recording 

 instruments. The chief novelty is that the glass receiver 

 is permanently fi.xed to the funnel, and by means of a tube 

 the contents can be emptied for measurement into an 

 ordinary measuring glass. The latter is conical below, so 

 that the graduation of small quantities of rainfall may be 

 more accurately measured than is the case in an ordinary 

 glass. A somewhat similar arrangement was proposed by 

 Mr. John Aitken, F.R.S., in the same magazine in 1902, 

 and Dr. Mill then pointed out that in Prof. Hellmann's 

 rain gauges, used at official stations in Germany, the 

 measuring glasses are constructed on the principle sug- 

 gested by Mr. Aitken, the graduation of the first lomm. 

 being fifteen times as long as the others. The " Camden " 

 rain glass recently designed by Messrs. Negretti and 

 Zambra is also conical at the lower end. This arrange- 

 ment enables the observer to decide, without guessing, 

 whether in cases of very slight rainfall the amount is nearer 

 o.oi inch than 0.00, and consequently whether the day 

 should be counted as a " rain-day " or whether the precipi- 

 tation should be disregarded. 



A NEW self-recording mercurial barometer has been 

 devised by Mr. W. H. Dines, and is a much improved form 

 of the instrument known as Milne's barograph. Its basis 

 is, therefore, a glass syphon mercurial barometer, having 

 its shorter limb, and a length of the upper portion of its 

 longer limb, of considerably wider calibre than the re- 

 mainder of the tube. In the shorter limb of the Dines 

 pattern of the instrument, an iron float, of peculiar con- 

 struction, moves freely, and through the medium of flexible 

 lines connected to the arched heads of a lever-beam (or 

 NO. 181 I, VOL. 70] 



differential pulley) multiplication arrangement, this float 

 actuates the recording pen. The clock movement is of 

 Richard's type, and is enclosed within a long but light 

 ebonite cylinder, which it drives, and on the outside of 

 which is wrapped the chart (all the divisions on which are 

 rectangular). The principal feature of Mr. Dines's new- 

 pattern of the instrument is a neat temperature-com- 

 pensating arrangement embraced in the float. The iron 

 float is essentially a cylinder, sealed and weighted at the 

 top, but open underneath, below the level of the mercury 

 in the short limb of the syphon, and when in position the 

 cylinder contains air. It will be evident upon consideration 

 that, given a suitable amount of air within such a float, 

 the effect of the expansion (say) of that air on the occurrence 

 of an increase of temperature will compensate for the 

 alteration in the level of the mercury in the short limb of 

 the syphon resulting from the expansion of the mercury 

 in a syphon barometer having relatively wide upper and 

 lower ends. Mr. Joseph Baxendell informs us that the 

 latest pattern of the new instrument now in use at the 

 Fernley Observatory, Southport, has been rendered prac- 

 tically frictionless, and that the Dines float modifications 

 include a means of overcoming the errors commonly arising 

 from the varying capillary effects occasioned by the reversal 

 of the direction of motion of the mercury in the syphon. 



Prof. George A. Gibson, writing in the Proceedings of 

 the Edinburgh Mathematical Society, vol. xxii., directs 

 attention to a weak point in the conventional treatment of 

 tangents to circles and curves by the method of limits. 

 In proving the tangent to be perpendicular to the radius, it 

 is shown that when a straight line meets a circle in two 

 points A, B, the line makes equal angles with the radii 

 0\ and OB, and since this is the case however near B is 

 to A, it is said, " therefore the same result is true when 

 B coincides with A." But, as Prof. Gibson points out, it 

 would be equally logical to say that if 0.\ is the perpen- 

 dicular from O on a straight line, E any point on that 

 line, OE>OA, however near E may be to A, and " there- 

 fore " the same is true when E coincides with A, which 

 is of course absurd. The author remarks, " It is rather 

 disheartening to find the absurdities, so clearly pointed 

 out by Berkeley nearly two hundred years ago, still flourish- 

 ing and apparently endowed with a new lease of life." 



We have received the new volume of Dr. Otto Baschins's 

 " Bibliotheca Geographica," covering the literature of 

 geography to the end of 1900. The new issue does not 

 contain any important new features, but it completes the 

 first decade of a work recognised for its accuracy and 

 exhaustiveness. 



The Soci^t^ d'Encouragement pour I'lndustrie nationala 

 has published a valuable paper on the Port of Rosario as a 

 supplement to its May Bulletin. The author is M. Georges 

 Hersent, and the paper deals fully with the past, present, 

 and future of the seaport. Useful information about the 

 economic geography of the Argentine generally is also to 

 be found in an introductory chapter. 



Among the most important recent additions to the carto- 

 graphy of Canada are a map of south-eastern Alaska and 

 part of British Columbia, showing the award of the Alaska 

 Boundary Tribunal, and a map of the North-West Terri- 

 tories and the province of Manitoba. The former is re- 

 duced from the original Canadian Boundary Commission 

 map to a scale of i : 960,000, and contours at looo-feet 

 intervals are retained. The map of Manitoba is on a scale 

 of 12J miles to an inch. 



