January 23, 1913] 



NATURE 



565 



ticity of materials, the theory of spring's, safety 

 and dangers in structures and the testing- of struc- 

 tures, on units, on dimensional equations, on 

 absolute motion, on fatigue of materials are less 

 well known, but students who read them will get 

 a clear insight into subjects on which text-book 

 reasoning is sometimes rather slipshod. His 

 paper on the parallel roads of Lochaber is acknow- 

 ledged to have cleared up a great geological 

 puzzle. His paper on prismatic structure in 

 basaltic rocks cleared up the Giant's Causeway 

 puzzle. 



In his paper of 1872 on atmospheric refraction 

 of inclined rays and on the path of a level ray 

 he solved another important problem. His 

 integrating machine is now in use for tide-calcula- 

 tion. There are many papers on subjects of general 

 interest to which I cannot refer because I have 

 no space. Suffice it to say that on every subject 

 about which he wrote he threw a new light, he 

 g'ave fresh ideas, and he started students on new 

 lines of thought. In reading one of his papers we 

 instinctively feel sure that he has given long and 

 careful consideration to the matter and has looked 

 at it from many points of view ; consequently he 

 has exact and clear ideas, and he is able to state 

 them in simple language, so that we at once 

 accept his conclusions as correct. 



John Perky. 



TABLES OF THE WEIGHT OF AIR. 

 Tabellen der Lujtgcwichte y,', der Druckdqui- 



valente /?' und der Gravitation g. 

 Tables des poids de I'air y'/, des Equivalents 



baromdtriques P'l et de la gravity g. 

 Tables of the Weight of Air yf, of the Air- 



Pressure Equivalents /3? and of the Gravity g. 



By Dr. S. Riefler. Pp. iv+ioi. (Berlin: 



Julius Springer, 1912.) Price 6 marks. 



IN rough experiments, the density or the weight 

 of the air may often be ignored ; generally, 

 however, it is allowed for with more or less com- 

 pleteness. But when it is desired, as in the 

 author's work, to make a precise determination, 

 so precise that the effect of moisture in reducing 

 it, or carbonic acid gas in increasing it, must not 

 be ignored, and when the local value of g has 

 to be allowed for, then the investigator may find 

 the calculation to be unduly tedious. 



The author of these admirable tables has been 

 brought face to face with the difficulty in con- 

 nection with the disturbing effect of the density 

 of the surrounding air on the period of the pendu- 

 lum of the astronomical clock. For instance, the 

 Tate of such a pendulum is changed by i/ioo 

 second per day, so he states, by a variation in 

 NO. 22S6. VOL. Qol 



weight of one milligram per litre in the air 

 surrounding the pendulum. He has, therefore, 

 calculated a series of tables, where they were not 

 already in existence, whereby all the data required 

 can be found with the maximum of directness and 

 accuracy and the minimum of trouble. Every 

 table has the formula on which it is based printed 

 at the head, and a clear statement of the whole 

 problem is printed in three parallel columns in 

 German, French and English. In only one case 

 is this departed from, where the names of the 

 countries in which a large number of stations are 

 situated for which or has been determined are 

 printed in English only, "on account of the 

 extended use of this language " — a compliment 

 which an English paper should acknowledge. 



The most important of the tables is calculated 

 for every 10 mm. of barometric height from 380 

 to 680 mm., and then for every mm. up to 790 

 mm., and for every degree of temperature from 

 — 1° C. to +36° C. For all these conditions the 

 weight of a litre of air free from CO.,, but both dry 

 and half saturated with moisture, is calculated on 

 the basis that at Paris the weight of dry air free 

 from moisture and COj is, under standard condi- 

 tions, i293"2i mg. Alongside the figure giving 

 the weight is another, called by the author "the 

 pressure equivalent of temperature," which shows 

 the change in pressure in mm. of mercury due 

 to a change of i° C. in temperature. It is interest- 

 ing to notice that this, in the case of half-saturated 

 air at 760 mm., has a minimum value at about 



17° C. 



It would require more space than is available 

 to discuss the tables fully. It is sufficient to say 

 that the printing, the paper and the arrangement 

 are all admirable, and that these tables should 

 be found in every laboratory where exact work is 

 done. C. V. B. 



ANTHROPOLOGY AND ARCHAEOLOGY. 



(i) The Annual of the British School at Athens. 

 No. xvii. Session 1910-11. Pp. liv + 355 + xxi 

 plates. (London : Macmillan and Co. , Ltd. , 

 1912.) Price 2^s. net. 



(2) The Cochin Tribes and Castes. 

 Anantha K. Iyer. Vol. ii. Pp. 

 (Madras : Higginbotham and Co. 

 Luzac and Co., 191 2.) 



(3) The Origin of Civilisation and the Primitive 

 Condition of Man. Mental and Social Condition 

 of Savages. By the Right Hon. Lord Avebury. 

 7th edition. Pp. xxviii -|- 454. (London : Long- 

 mans, Green and Co., 1912.) Price js. 6d. net. 



(4) Notes and Queries on Anthropology. Edited 



By L. K. 

 xxiii + 504. 

 : London : 



