October 31, 1907 J 



NA TURE 



663 



interpretation of all these facts except that under natural 

 conditions fluctuations are selected and inheritance is 

 blended ? 



He lays stress on the circumstance that man is not 

 amenable to experiment ; but man is not the only species 

 that has natural varieties. May I, in turn, lay stress on 

 the fact that it seldom pays the cultivator to select small 

 differences (fluctuations)? Of necessity he selects muta- 

 tions. The Mendelian experimenter has practically liinited 

 himself to the materials so created. He himself chooses 

 for his experiments, and can choose, only glaring differ- 

 ences. In other words, he has, qua experimenter, abso- 

 lutely no acquaintance with the small differences (fluctu- 

 ations) which normally distinguish mating individuals in 

 natural breeding. He judges the normal from the 

 abnormal, the rule from the e.xception, and then appeals 

 to earth to note the precision of his methods and thanks 

 heaven he is not as other men, even as mere observers 

 who seek to take the whole of the facts into consider- 

 ation. Notwithstanding his parade of exactness, his belief 

 that he reproduces natural conditions " is an assumption 

 wliich still lacks the support of facts." Once more, there- 

 fore, let me challenge Mr. Lock and his comrades. If 

 Mendelism deals with any other problem but that of sex, 

 what is that problem? If no other problem can be named, 

 W'hat is the evidence that Mendelism deals with anything 

 more than those abnormalities of sexual reproduction which 

 occur under conditions of artificial selection? As I say, I 

 do not ask for the solution of any problem. I ask only 

 for an indication that Mendelism has any conceivable bear- 

 ing on it. If the latter question also cannot be answered, 

 then by all means let Mendelians pursue their very interest- 

 ing studies ; but let it be understood that " the new 

 science of genetics " implies, not the study of heredity 

 in general, but only the studv of certain curiosities of 

 artificial breeding. G. .Arciidall Reid. 



Southsea, October 20. 



Pagan Survivals and Christian Adaptations. 



It may interest some of the readers of Nati're to find 

 that the institution of the " kern-baby " (corn-baby) 

 still exists in our island ; and a writer in the Christian 

 World for October 3 was present at the bringing home, 

 on the last load, of this Pagan institution, and was present 

 at the harvest supper this year, when the effigy was 

 honoured by being placed on the table. It was, pre- 

 sumably, only a survival of olden time, when our ancestors 

 " ate and drank " with their gods — especially the gods of 

 agriculture (Judges, 9, v. 27). 



.Again, I received a letter the other day from the rector 

 of Fobbing, Essex (formerly rector in the Scillv Islands), 

 informing me, in reply to an inquiry, that the Beltane 

 fires are, up to the present day, lit there on the highest 

 point of the islands on May eve, just as our ancestors lit 

 them in honour of the rise of Baal (or the sun). My 

 informant, who has only left the islands two years, often 

 witnessed the jumping of the youths "through the fire." 

 I should be verv pleased to learn of any ancient customs 

 of this kind still carried out on the eves of " M.ay Day," 

 "Easter," ".Ml Hallows," "Christmas," or other 

 solstitial and equinoctial periods, and not heretofore re- 

 corded in standard books on the subject. In trying to 

 ascertain the uses of certain stone circles and monster 

 cromlechs this evidence is of great importance, as the 

 early missionaries purposely " adapted " so many of the 

 Pagan festivals to Christian worship. Wales is the most 

 promising field. J. W. Haves. 



West Thurrock Vicarage, Grays, Essex, October id. 



The " Quaternary." 



In reply to Dr. Wright's comment on my letter (p. 639), 

 I would point out that the restricted use of the word 

 " Quaternary " appears to be confined to anthropologists. 

 Geologists (Sir Archibald Geikie, Prof. Kaysor. and Prof. 

 Lapworth, for instance) who employ the term include in it 

 everything from the commencement of the Glacial period 

 to the present time. John W. Evans. 



Imperial Institute, October 25. 



NO. 1983, VOL. 76] 



THE " MAURETANIA." 



T^HE first impression of the Maiirctaiiia is one of 

 ■* colossal size, the last is wondering amazement at 

 the forethought and design which appear in de- 

 tails, trivial in themselves, but of supreme import- 

 ance to individual comfort, of the fittings. Only those 

 who saw the ship in the narrow waters of the Tyne 

 can realise her huge dimensions. Eight hundred feet 

 long herself, she floated abreast the builders' yard in 

 a river less than 900 feet wide, which runs in a nar- 

 row cleft between low hills. In that narrow vallev 

 the great bulk of the ship made a prodigious 

 spectacle, and over the valley before the start on the 

 maiden voyage the smoke from her four great 

 funnels moved like a pall. 



In the brief voyage from the Tyne to the Mersey 

 which took place last week, some of the peculiar 

 features of the great ship were revealed. The Tvne 

 is winding and narrow, and on the Tuesday afternoon 

 its course was obstructed by crowds of steamers laden 

 with sightseers. In this difficult passage the handi- 

 ness of the vessel was at once apparent. Proceeding 

 under her own steam, steered by propellers and the 

 rudder, she was easily manoeuvred at the sharp bends. 

 To the writer, who was on the bridge at the time, it 

 was obvious that the great turbines, which in the 

 aggregate can develop 70,000 h.p., can be stopped or 

 started with ease and certainty. 



.\t sea, though the recurrent shocks characteristic 

 of vessels fitted with reciprocating engines are absent, 

 vibration is noticeable, though relativelv slight. 

 Generally speaking, it is maximal in the after part 

 and diminishes thence to the bows. The distribution, 

 however, is erratic, regions of maximal vibration often 

 being close to regions of minimal vibration. In the 

 great dining saloon at 22 knots the tremors were 

 barely noticeable, being s'jmething like the passage of 

 a vehicle in a street outside. On the other hand, a 

 region of marked vibration was forward of this, about 

 the level of the second funnel. 



The cause of the vibration in turbine-propelled ships 

 is not at all obvious, and experts at present seem to 

 be unprovided with a satisfactorv hypothesis. The 

 turbines themselves are singularlv free from it. 

 Leaning against their great steel shells one is noi 

 con.scious of a movement. In the shaft tunnels, how- 

 ever, it is very marked. The vibration has been re- 

 ferred to the impact of the water thrown bv the 

 blades of the wing propellers against the sides of the 

 ship, to the unequal thrusts which each blade exerts 

 in the course of each revolution, and to the formation 

 of twisting couples between the propellers when they 

 svnchronise in certain ways. Inequalities in the 

 thrust arise from the fact that owing to skin friction 

 the water near the side of the shio is dragged bodily 

 along with it. Each blade, therefore, as it revolves, 

 passes through water moving in the direction of the 

 shio to water which, relatively speaking, is still. 



The vibrations themselves are markedly periodic, 

 mounting bv a long crescendo to a climax, followed 

 usually bv complete quiet. This periodic nature un- 

 questionably suegests a dependence upon synchronism 

 between propellers on opposite sides of the ship, and 

 it was foimd in the ca.se of, I believe, the Deutsch- 

 laiid that vibration was much lessened when her 

 twin screws were set to rotate respectively at 70 and 

 80 times a minute instead of both beine at approxi- 

 mately the same rate. The whole subject is being 

 investigated on the Maiiretania by means of the 

 pallograph, which registers at the same time the 

 shaft movements and the vibrations. 



As it is not possible to get an indicator diagram 

 of a turbine, the work done is measured on the 



