November 8, 191 7] 



NATURE 



195 



attempts to correct the aim by automatic sights have 

 been made, but the most effective measure is to fire 

 as many rounds as possible during the combat ; hence 

 the frequent duplication of a forward fixed gun. 



M. Lefranc concludes his article with a brief descrip- 

 tion of the types of bullet used by the Germans. He 

 mentions four types : the ordinary bullet, the perforat- 

 ing bullet for destroying the engines and metal parts 

 of a machine, the incendiary bullet, and the explosive 

 bullet. The article is liberal'ly illustrated wnth sketches 

 and diagrams, and is well worthy of perusal. Any 

 attempt to trace developments further than M. Lefranc 

 has done would doubtless be censored ; indeed, some ten 

 lines of the article in question have been censored as 

 it is. We have, therefore, contented ourselves with a 

 brief resume of the most important points of the 

 article, as they will doubtless be of interest to those 

 who follow the progress of the scientific development 

 of aircraft. 



REPORTS ON CLIMATES. 



AN interesting memoir on the climate of Bagdad 

 ("Sul Clima di Bagdad"), by Prof. Fihppo 

 Eredia, appears in a recent issue of the Bollettino delta 

 Reale Societd Geografica Italiana, under the auspices 

 of which a mission was dispatched in 1908, led by 

 Dr. A. Lanzanr. Prof. Eredia summarises the more 

 salient features of this expedition's work, and 

 further utilises information given in various papers 

 bv Eliot, Hann, and Gilibert Walker. Bagdad is in 

 lat. 33° 19' N., long. 44° 26' E., the height of the 

 cistern of the barometer above sea-level being 

 127 ft. The mean barometric pressure at 32° F. 

 sea-level and lat. 45° is 29893 in., being highest, 

 30149 in., in January, and lowest, 29-543 in., in July, 

 a variation in the monthly means of o-6o in. The 

 mean annual temperature is 73-0° F., ranging from 

 945° in July and August to 48-9° in January. The 

 mean of the daily maxima is 86-o°, the mean monthly 

 values ranging from 109-9° in August to 59-5° in 

 January. The mean of the night minima is 6o-i°, 

 highest in July, 79-5°, and lowest in January, 38-1°. 

 The highest temperature recorded was 122°, and frost 

 is not uncommon from November to February. The 

 mean daily range of temperature varies from 33° in 

 August and September to 20° in December. The 

 relative humidity is 58, rising to 80 per cent, of 

 saturation in December and January, and falling to 

 38 per cent, in June. The mean cloud amount (over- 

 cast sky=ioo) is only 16, the extremes being 29 in 

 March and i in July. Various authorities place the 

 annual rainfall between 6-94 in. and 904 in., practically 

 all of which falls between November and April. 

 June, July, and September are rainless, but slight 

 showers have fallen in May, August, and October. 



A useful paper appears in the Bollettino d'lnforma- 

 zione (Anno iv., N. 7-8-9) of the Italian Ministry 

 for the Colonies, by Prof. Eredia, on the climate of 

 Derna, an important commercial centre of Bengasi, 

 situated in lat. 32° 45' N., long. 22° 40' E. Some 

 fragmentary data collected by previous writers is 

 first summarised, but the greater part of the paper 

 is taken up with a discussion of observations extend- 

 ing from March, 1913, to December, 1915, made with 

 a complete instrumental installation. The observa- 

 tions made at 9 a.m., 3 p.m., and 9 p.m. are col- 

 lected in ten-day periods for each of the three hours. 

 The mean annual temperature is 68° F., of August, 

 the warmest month, 78-3°, and of January, the coldest 

 month, 57-4°. The extremes noted have been 112° 

 and 40°. The mean annual barometric pressure is 

 exactly 30 in , showing a range of 0-17 in. between 

 December (the month of highest pressure) and July 

 NO. 2506, VOL. 100] 



(the month of lowest pressure). The annual rainfaU 

 is 7-94 in., of which 86 per cent, falls bet;ween Novem- 

 ber and February. There are fifty-one days in the- 

 year with precipitation, July and August being rain- 

 less. In spite of the small rainfall heavy downpours- 

 are occasionally observed. Thus 3-13 in. have fallen' 

 in two days, and three daily falls exceeding an inch 

 have occurred. The prevailing wind, except in De- 

 cember and January, is north-west, one result of this- 

 being the remarkable steadiness of the relative 

 humidity, which in no month differs appreciably from 

 the annual mean of 62. The mean amount of cloud 

 varies from 9 per cent, in July to 57 per cent, in 

 February. 



Prof. Eredia discusses in vol. xxvi. of the Rendi- 

 conte della R. Accademia dei Lincei the monthly 

 variations of barometric pressure at twelve places in 

 Italy, based on data for the thirty-five years 1881-1915. 

 The maximum is in January and the minimum in 

 April at all stations. At Pesaro, Florence, Rome, and 

 Lecce there is a well-marked secondary minimum in 

 July. The variation in the monthly means diminishes 

 appreciably with latitude, the amplitude between the 

 months of highest and lowest pressure being 0-07 in. 

 less on the southern coasts than at northern inland 

 stations. Prof. Eredia also contributes a paper, " Le 

 Brine in Italia," to a recent issue of the Bollettino 

 Bimensuale della Societd Meteor. Ital., in which he 

 summarises the results of an investigation into the 

 frequency of hoar frost in Italy. The mean monthly 

 number of cases is given for fifty stations well dis- 

 tributed over the country for the five months, Novem- 

 ber to March, during the twenty years ending 1915. 

 The greatest number of cases is in January, closely 

 followed by December. Pavia, in Lombardy, has an 

 average of forty-one cases during the five months 

 under consideration, whilst at Naples the mean fre- 

 quency is only 0-4. In most districts coastal stations 

 have a relatively small number of cases as compared 

 with inland stations contiguous. The distribution of 

 pressure and also lo':al conditions favourable to the 

 production of hoar frost are discussed in considerable 

 detail. The insertion of a small map showing the 

 position of the stations utilised would add much to 

 the interest of Prof. Eredia's valuable investigations 

 into various phases of Italian climatology. 



R. C. M. 



EVOLUTION OF THE PRIMATES. 



DR. W. K. GREGORY, of the American Museum 

 of Natural History, New York, has contributed 

 to the Bulletin of that institution a series of studies on 

 the " Evolution of the Primates." In part i. he re- 

 views the theory of cusp-formation which was 

 first formulated by Cope and afterwards elabo- 

 rated and perfected by Osborn, and contends 

 that all later discoveries have justified their 

 supposition that the upper molars of primates 

 (and also of all typical placental mammals) are modi- 

 fications of a common tritubercular type, while the 

 lower molars are modifications of a " tuberculo-sec- 

 torial " form. In his opinion the similarity of the 

 molar type in all forms of man and anthropoid, both 

 living and extinct, is a matter beyond dispute. 



In part ii. Dr. Gregory discusses the phylogeny of 

 the known anthropoid and human types. He regards 

 the chimpanzee and gorilla as man's nearest allies, 

 and, on the present evidence, thinks the commori stock 

 from which all three arose may have been in existence 

 during the Miocene period. His review of the dental 

 characters of extinct anthropoids is most welcome. 

 He cannot agree that the genus Sivapithecus, recently 

 described by Dr. G. E. Pilgrim, of the Geological 

 Survev of India, stands in the direct line of human 



