April 28, 1910] 



NATURE 



259 



are tabulated and discussed. The hourly values of the 

 three magnetic elements are given in full with the times 

 and values of the absolute maxima and minima, the 

 differences, and the characters of the curves, morning and 

 evening. Then follow valuable risumis in several forms, 

 and lastly is given a series of notes directing special 

 attention to the exceptional disturbances of the year, the 

 curves for which appear amongst a number of excellent 

 curves at the end of this section. Other sections deal 

 with the solar observations — useful for comparison with 

 the variations of the magnets — the soil temperatures at 

 various depths, and the seismological records, making the 

 work a valuable source of information to anyone engaged 

 on geophysical problems. The previous fascicule of the 

 same volume dealt with the material collected in 1907, 

 and the index now published shows the contents of the 

 volumes that have appeared, with interruptions, since 1834. 

 In the preface M. Lecointe, the director, pays a fitting 

 tribute to the conscientious and enthusiastic labours of 

 Captain Louis Niesten, who, after thirty-two years' service, 

 has retired from the observatory staff. Practically all the 

 observations now published were made by M. Somville. 



The Wabash Railroad Company, U.S.A., was one of 

 the pioneers in the use of reinforced concrete, and some 

 of their methods of construction were described in a paper 

 read at the Institution of Civil Engineers on .April 19. 

 This company commenced the use of this form of con- 

 struction for bridges, culverts, subways, and retaining walls 

 in 1902. "Not any of these structures have required any 

 repairs since they were built. They are very rigid under 

 loads, and their appearance indicates that they will out- 

 last any other kind of structure, and require no mainten- 

 ance. Attempts have been made to determine the deflec- 

 tion in reinforced concrete structures due to train loads, 

 but none can be detected under ordinary measurement. 

 The unit stresses allowed are as follows : — for steel in 

 tension, on net section of rod, 18,000 lb. per square inch ; 

 for steel, bond on deformed bars, 100 lb. per square inch ; 

 for concrete, compression in cross-bending, 800 lb. per 

 square inch ; for concrete, direct compression, 600 lb. per 

 square inch; for concrete, shear (diagonal tension) in 

 plain concrete, 30 lb. per square inch ; for concrete, shear 

 (diagonal tension) where the web is properly reinforced, 

 100 lb. per square inch. The concrete used consists of 

 one part of Portland cement, two of sand, and four of 

 stone or gravel. Prof. Talbot's rules were employed for 

 proportioning the concrete and steel. The concrete was 

 put in as a wet mixture, securing a more dense and 

 homogeneous concrete, and imbedding the reinforcement 

 better, thus preventing rusting of the metal. 



Mr. C. Baker's classified list (No. 44, April) of second- 

 hand instruments for sale or hire contains particulars of 

 about 1600 pieces of scientific apparatus. The apparatus 

 includes optical instruments of all kinds, and many other 

 appliances and accessories required for instruction or 

 research. 



A SECOND revised edition of an excellent handbook, 

 " Brazil in 1910," by Mr. J. C. OakenfuU, has just been 

 issued by the author, 21 Clifford Terrace, St. Budeaux, 

 Devonport. The work has been brought up to date, and 

 is well illustrated by reproductions of photographs and 

 several maps. There are many statistical details, and an 

 appendix giving information as to salaries and cost of 

 living. The main theme of the writer is that Brazil offers 

 abundant opportunities for the activities of Europeans with 

 capital. 



NO. 21 13, VOL. 83] 



OVR ASTRONOMICAL COLUMN. 



Astronomical Occurrences in May: — 

 May 2. 4h. Mercuiy at greatest elongation (20" 55' E.). 



,, 8h. 32m. to loh. 57m. Transit of Jupiter's Satellite 

 III. (Ganymede). 

 4-7. Meteoric shower before sunrise from Halley's comet ? 



8. ijh. Sun eclipsed, invisible at Greenwich. 



9. Iih. 59m. to I4h. 2611). Transit of Jupiter's Satellite 



III. (Ganymede). 



10. oh. Mercury 1° 18' N. of the Moon. 



11. iih. 52m. Minimum of Algol (/3 Persei). 

 14. 8h. 41m. ,, ,, ,, 



18. I4h. Halley's comet transits the Sun's disc. 

 23. Moon eclipsed, partly visible at Greenwich. 



I4h. 33m. First contact with penumbra. 



ISh. 47m. ,, ,, shadow. 



I5h. S7m. Moon sets at Greenwich. 



The Total Solar Eclipse of May 8, 1910. — This 

 eclipse, which can be observed from Tasmania, is not a 

 very favourable one, because the sun at the critical time 

 is only about 8° above the horizon. Mr. Frank McClean, 

 however, who has made considerable preparations for 

 observing it, is already in Tasmania, and has collected 

 a party of eight observers to help him utilise the numerous 

 instruments he has taken out with him. The point he 

 has settled upon as his observing station is situated in the 

 south-west part of the island, namely, Hixson Point. 

 Bramble Cove, Davey. In a cable to Dr. Lockyer. dated 

 -April 19, 11-55 a.m., he states: — "Sunday extensive 

 scrub fire within four feet instrument tent. No damage." 

 While on the occasion of his successful expedition to Flint 

 Island in 1908 his chief enemy was " water," he has now 

 Jiad to combat " fire." Little is known at present about 

 the site, but in a letter to the recipient of the cable he 

 writes that one of his party " is as strong as a horse," 

 and will be exceedingly useful " when we have to clear the 

 200-feet high trees out of the way and carry the packing 

 cases up a 600-feet hill." It will thus be seen that he is 

 making every endeavour to secure as good a site as 

 possible, and it is hoped that his energy will be rewarded 

 with success. 



Halley's Comet. — Reports from a number of places 

 state that Halley's comet has been seen as a fairly bright 

 object, under favourable conditions, with the naked eye. 

 Cloudy weather has seriously interfered with English 

 observers, but the comet was seen, and estimated to be 

 of the second magnitude, at Greenwich on the morning 

 of .April 25, and was followed until nearly sunrise. .Accord- 

 ing to the Times report, it was probably seen with the 

 naked eye, and photographs were secured with several 

 instruments. Owing to the brightness of the sky, ex- 

 posures of one minute only were possible, and the result- 

 ing plates show only the nucleus and coma, with no refer- 

 ence stars. The appearance of the comet was that of a 

 small whitish cloud with a brighter nucleus. The Times 

 also states that good positions of the comet were secured 

 by Dr. Ristenpart, at Santiago, on .April 12, 15. and 21, 

 and that he has re-determined the time of perihelion 

 passage as .April 19-6803 (G.M.T.). about an hour later 

 than was determined by Mr. Merfield. Observations by 

 Mr. Ryves at Saragossa, Spain, on April 21, showed, 

 from naked-eye comparisons with y Pegasi, that the 

 magnitude was about 2-7. Mr. Innes also reports a 

 naked-€ye observation at Lyme Regis on .April 25, between 

 4h. and 4h. 30m. a.m. Similar observations are reported 

 from Malta and Gibraltar, and, at the former, a tail about 

 1° in length, and inclined about 40° to the horizon, was 

 seen. 



In No. 16 of the Comptes rendits (p. 955, April 18) 

 M. Giacobini reports having observed the comet, at the 

 Paris Observatory, between i6h. and i8h. on .April 17. 

 He was surprised at the increase in brightness since 

 March 7, when the magnitude was estimated as 9-5 ; at 

 present he estimates it as 20 or 2-5. Taking the ephemeris 

 values for the distances from the sun and earth, this 

 means that on May 18, 19, and 20 the magnitude should 

 be — 1-3 to — 1-8, as bright as, or brighter than, Sirius. 

 To M. Giacobini the comet appeared as a circular nebu- 

 losity 30* to 35* in diameter, with a strong central con- 



