758 



NATURE 



[August 12, 1920 



Meteorological observations made at secondary 

 stations in Netherlands East India have recently been 

 published for 1917. Since the publication of the 

 previous volume a well-equipped meteorological station 

 has been started at the aerodrome at Sockamiskin. 

 Cloud observations have been almost wholly discon- 

 tinued, and sunshine records are substituted ; the 

 cloud estimations (o-io) are said not to be trustworthy 

 — which is scarcely surprising, since it is stated that 

 the lower half of the sky was not taken into account, 

 and that density had its say. Sunshine observations 

 are from Jordan recorders, but the Campbell-Stokes 

 recorder would give results more comparable with 

 European observations. In addition to the ordinary 

 detailed observations of rainfall, tables under the head- 

 ing of "cloud-bursts" are given practically for all 

 stations," which show the individual instances of rain- 

 fall of I mm. and more per minute, the minimum 

 duration being' five minutes. At Batavia the maxi- 

 mum mean monthly air-pressure occurred in August, 

 and the minimum in April. July was the warmest 

 month and December the coldest. The mean relative 

 humidity, saturation being expressed as 1000, 

 rang-ed from 879 in February to 793 in August. 

 The percentage of bright sunshine was greatest 

 in August and least in January. By far the 

 greatest amount of rain falls in the winter months, 

 January being the wettest, whilst May and June 

 are the driest months. Wind results are given at only 

 a few stations, but the observations clearly indicate a 

 diurnal range in direction and velocity. A more com- 

 plete discussion of winds would be of value for aero- 

 nautics, whilst the moveiment and, if practicable, the 

 height and speed of clouds would add much to a 

 better knowledge of the upper air. 



The Bulletin de la Societe d' Encouragement pour 

 rindustrie Nationale for March-April gives a full 

 report of the work of M. Martial Entat on the 

 tiestructive effect of light on certain materials such 

 as textiles, dopes, and rubberised fabrics. It is diffi- 

 cult, if not impossible, in these climates to make 

 quantitative measurements of the effect in the case 

 of sunlight, and M. Entat accordingly used ultra-violet 

 light from a mercury-vapour lamp in his experiments. 

 He found that the mercury lamp was twenty times 

 as effective as full sunlight in its destructive action 

 on such materials. As is now well known, consider- 

 able protection may be afforded by the use of various 

 dyes for absorbing the ultra-violet light. M. Entat's 

 experiments indicate that the dyes commonly em- 

 ployed in aviation for protecting the fabric of aircraft 

 have a "coefficient of protection" of from 50-75 per 

 cent., the most efficient being the red dye from quino- 

 line. A spectrographic measurement of the absorption 

 of the ultra-violet light placed the various dyes in 

 the same order as the tensile tests on the dve- 

 protected fabrics which had been exposed to the rays. 

 Experiments similar to those of M. Entat were carried 

 out during the war at the Royal Aircraft Establish- 

 ment at Farnborough. An account of the work was 

 given by Dr. Aston to the Royal Aeronautical Society 

 last year. 



NO. 2650, VOL. 105] 



No. 4 of Abstracts of Papers in Scientific Trans- 

 actions and Periodicals, published as a supplement to 

 the minutes of the Proceedings of the Institution of 

 Civil Engineers, contains a large number of brief 

 abstracts taken from papers and periodicals published 

 outside the United Kingdom. These are classified 

 under the main headings of (i) measurement, 

 measuring, and recording instruments ; (2) engineer- 

 ing materials ; (3) structures ; (4) transformation, 

 transmission, and distribution of energy ; (5) 

 mechanical processes, appliances, and apparatus ; 

 (6) specialised engineering practice; (7) economics, 

 etc. There are several subdivisions to each of 

 these main headings. It is not easy to produce 

 abstracts which shall contain the information re- 

 quired and thus obviate the necessity for those 

 interested having to consult the original papers ; we 

 note that these abstracts are satisfactorv in this 

 respect, and therefore provide a mine of information 

 which we trust will be available to engineers who 

 are outside the ranks of the Institution of Civil 

 Engineers and would gladly purchase the Abstracts. 

 The editing is somewhat loose occasionally ; thus we 

 note on p. 16 that an acceleration has been stated 

 as "slightly more than 2 ft. per sec." A slip of this 

 kind would have to pay a penalty at the institution 

 examinations. 



The special requirements in dental radiographv are 

 met by the radiator dental type of Coolidge tube, 

 obtainable from the British Thomson-Houston Co., 

 Ltd. This embodies the original features of the 

 radiator type of tube whereby a large portion of the 

 heat generated is conducted away bv a copper radiator, 

 but, in addition, the new tube allows greater proxiniit\ 

 of the anode to the part under exposure. The cathode- 

 arm extends 2 in. from the bulb at right angles to 

 the anode-arm ; this method of construction secures 

 the emission of the X-rays in a .line with the axis of 

 the anode. The cathode circuit is earthed, so that 

 there is only one high-tension wire, which is con- 

 nected to the part of the tube most remote from 

 the subject under exposure ; this allows a minimum 

 distance between the dental film and the focal spot, 

 with consequent reduction in the time of exposure. 

 The tube is self-rectifying within the limits of its 

 allowable energy output, and is designed for an input 

 not exceeding 10 milliamperes at an alternative spark- 

 gap of about 3 in. The tube being designed to run only 

 under specified electrical conditions, the manipulations 

 are reduced to a minimum, and the only variable left 

 in the hands of the operator is the time for which the 

 film is to be exposed. In dental radiography this 

 attempt at sta-ndardisation and simplification of pro- 

 cedure is likely to m^^et with considerable success. 



Mr. a. Thorburn, whose sumptuous volumes, 

 "British Birds" and "A Naturalist's Sketch Book,'' 

 have been so well received, is bringing out through 

 Messrs. Longmans and Co. a companion work 

 entitled "British Mammals." It will be in two 

 volumes and contain fifty plates in colour and many 

 illustrations in black-and-white. Vol. i. is promised 

 for the coming autumn, and vol. ii. for the spring of 

 next year. 



