2l8 



a yellow, in a. Id ii ion 

 originally ust-d 1 ! 



gives th(! colon I 



III. 



NATURL 



[Dece: 



pink, and rt*<l i montore, the most souther 



.iiiU .11. 



m;Ii( (lull 



lid.. I.-, V. 



d.Mlil. 



lll^llliyUlsli 



siiowin^ lli 



ill u hicli it is 



h.i\ iiu 

 Willi" 



ill ill'- I 

 ill. it ihi 



lOlllCl' 



\V(nild 



ih 



Lir vision 

 ■ appealed . 



iiteresting to know botii on wiiat grounds 

 iriginally rejected and on what grounds they 

 were ultimately p.i !ii>r ilusr an' ili'- N'Tv 



cases in whicii tin - ' iitv ui ihc ni> tlu»d> ul 



rxaininatidii cinijhiyi d may possibly be callrd in ques- 

 lion ai .sumo tiiUiie time. The matter is perhaps of 

 less importance, as we read in the report that " the 

 whole question of sight tests is now being carefully 

 considered by a Departmental Committee appointed 

 for the purpose," and it is therefore possible that 

 changes both of procedure and of record may be 

 suggested. 



Of the 112 men rejected for defective colour vision, 

 42 were completely and 21 incompletely jijrecn blind, 

 and 32 were completely and 17 incompletely red blind, 

 no instances of the rarer varieties of failure being 

 recorded. The rejections are somewhat in excess of 

 those of many previous years, and the explanation 

 seems to be that the fishermen seeking certificates, as 

 mentioned above, have only been required to pass the 

 same sight tests as candidates for certificates as 

 masters or mates in the mercantile marine since 

 November, 1909, and that they have increased the 

 proportion of defectives. As compared with the 

 amount of defective colour-sense in the population 

 tjt'ncrallv. tho proportion of rejections does not seem 

 iari^c, and it is highly probable that many colour- 

 blind persons are prevented, by a knowledge of their 

 condition, from attempting to enter the sea service. 



H /\ /) /y THE ADRIATIC AND IN HOLLAND.^ 



THERE has been in recent years a re-awakened 

 interest in the problem of the periodic variations 

 of the wind, but there remains much to be done to 

 complete that thorough harmonic analysis of the motion 

 of the air which Kelvin emphasised as one of the 

 most important lines of meteorological research so 

 long ago as 1876. Hitherto attention has been de- 

 voted mainly to a consideration of the semi-diurnal 

 variation, and the results have shown conclusively 

 that the regular semi-diurnal wave of pressure can, 

 as indeed it must, be connected through the hydro- 

 dynamical equations with a similar regular variation 

 of the wind-vector. In the discussion of the record 

 for individual places, the question of the local varia- 

 tions from the general law and their explanation 

 rightly find a place, but they ought not to be allowed 

 to exclude the consideration of other possible periods. 

 In the first chapter before us. Dr. Mazelle, Director 

 of the Observatory at Trieste, analyses five 3'ears' re- 

 cords from the Beckley anemograph erected in 1902 

 on a lighthouse in the Adriatic, the Klipper Porer, 

 which lies a mile and a half W.S.W. of Cape Pro- 



* " Die taeliche Period* der Windrichtiint; und Windstiirke n.ich den 

 anemometrischen Aufreichnunnen auf der Klippc Porer." By E. Mazelle. 

 Besonders_ Abjjedruckt aus detn Ixxxvii. Bande der Denk<;chtiften der 

 Matheraatisch-Naturwtssenschaftlichen Kla.sse der Kaiserlichen Akademie 

 der Wissenschaften. Pp. 65. (Wien : Alfred Holder, 1911.) 



"On tVie Diurnal Vari.ition of the Wind and the Atmospheric Pressure 

 •nd their Relation to the Variation of the Gradient." By Dr. J. P. ^-an der 

 Stok._ Pp. 14. Koninklijke Akademie van Wetenschappen te Amsterdam. 

 Reprinted fiom Proceedings of the Meeting of Afay 27, 1911. 



NO. 2198, VOL. 88] 



.Its iiunr'iu 111 i! 



frequent 

 giving til 

 for 



of the wind for 



i^'-us of the year shu.ss 

 !.. wind is must frequent, 

 ■ ■ 'i). '•• ■- ■ ■■ ---ni frcqu< . 

 ids are ii. 



. ....^ .';.M.ltw r I 



diurnal variation of the freqi 

 wind fi»r the eight urinLinal din t lions, ... 

 SAi. winds are i <ut 3 a.i 



\V. winds about ., , .\hicli in 



from land and sea bre' 



Diaj^ranis are drawn 

 tiuii ol the wind-Victor lor the four seasons and 

 tile whole year. In general the vector rotates ii 

 cln(kwi>i; direction in the course of the day, but 

 wiutc r the curve is looped and the rotation is cou:.- 

 clockwise from 3 p.m. to 3 a.m. The vari 

 greatest during summer, and is grea 

 spring than in autumn. It would have ! 

 an advantage if the results had been anal> 

 for the four principal directions, instead of for N. 

 S.E., N.VV., S.VV., in order to permit of direct c> 

 parison with results from other places and with the 



A considerable part of the paper is devoted to a 

 cussion of strong winds or gales, especially gales ff 

 the N.E. quadrant. Bora, and from the S.E. quadra 

 Scirocco. Dr. Mazelle takes a stormy day to be 

 on whicli the mean velocity of the wind is at U 

 50 kilometres per hour. There were 149 such days 

 the five years, or, roughly, one day in twelve. Janus 

 had 33 such days, or rather more than one in 6% 

 June, on the other hand, had only one such day 

 the whole period. A curious and suggestive peculis 

 is the secondary maximum in October, which 

 18 stormy days, compared with 11 in September 

 November. The diurnal variation on a stormy day 

 about the same in summer as in winter, the maximi 

 occurring at or slightly before noon in both seasc 

 For days of stormy Bora and Scirocco the definitk 

 is extended to include days on which the maximi; 

 velocity exceeded 50 kilometres per hour. There w« 

 233 days of stormy Bora and 71 of Scire 

 during the five years, a result which does not 

 gether support Horace's description of Scirocco' 

 Notus as "arbiter Hadriae," "that tumultuous rul 

 of the restless Adriatic." Bora is most frequent 

 winter, the worst month being January, with 

 average of eight days ; Scirocco is most frequent 

 autumn, with a maximum monthly average of 

 days in October. In every month the average num: 

 of days of Bora is greater than that of Scirocco. 



Perhaps the best idea of the character of Bora and 

 Scirocco is given by tables showing the length of the 

 periods during which the mean velocity exceeded 50 

 kilometres per hour, and of periods during which the 

 velocity never fell below 50 kilometres per hour. It 

 is seen from these that on one occasion of Bora 

 the wind blew^ uninterruptedly with a velocity cvceed- 

 ing 50 kilometres per hour for 144 hours, and that 

 on the same occasion the mean velocity did not fall 

 below 50 kilometres per hour for 7 daj's. The corre- 

 sponding maximum periods of duration for Scirocco 

 are 36 hours and 3 davs. The absolute maximum 

 velocity recorded durincr the five years was 128 kilo- 

 metres per hour for Bora. 102 for Scirocco, q8 for 

 S.W. gales, and 80 for N.W. gales. Unfortunately, 

 the factor of reduction i? not stated, so that it is not 

 possible to compare thesp value? with records for this 

 country. 



TTie second paper i? a discussion contributed 



