390 



NATURE 



{Feb.2\, 1889 



refer to the Bermudas as affording a good example of this 

 action : there, will be seen a great extension of the reefs on the 

 north-west side, and reefs are forming on the south-west — the 

 Challenger and Argus Banks ; and it should be noticed that 

 these are on the edge of the Gulf Stream, and also that there are 

 considerable eddy currents here which would cause a constant 

 supply of food to be brought to these parts of the islands; 

 whereas the conditions round tlie other parts of the islands are 

 not so favourable, and consequently there is no extension of the 

 reefs. 



I have been much puzzled by the curious formations of coral 

 reefs in the harbours of Suakim and Massaua and also round the 

 island of Key West ; and I have been unable to account for the 

 peculiarities in the shape of the fringing reefs except by an hypo- 

 thesis such as the above, in these cases the tidal currents taking 

 the place of the ordinary currents. 



David Wilson-Barker. 



The Earthquake in Lancashire. 



On Sunday, February 10, at 10.40 p.m., there was felt here 

 a shock as of a heavy falling body, which caused the windows 

 to rattle loudly. Two or three seconds later a second thud-like 

 shock was felt of somewhat greater intensity than the first. This 

 was followed by gentle but distinct tremors, lasting, perhaps, 

 twenty or thirty seconds more. The weather was calm at the time ; 

 the heavy snow-fall had just ceased ; barometer rising after the 

 considerable depression which had occurred during the day. The 

 sounds appeared to come from the north-east, as if a heavy body 

 had fallen outside a window having that aspect. Several other 

 persons name the same quarter as that whence the sounds seemed 

 to proceed, and in one instance, in a room having several aspects, 

 there was a distinct statement that the north windows were the 

 first to shake, then those in the south-west, thus indicating a 

 possible line of movement. In most cases no direction was 

 noted. Persons down-stairs thought something had fallen above, 

 those in the upper stories rushed down to see what had happened 

 below. Others, again, felt surrounded by the unwonted move- 

 ment. A heavy slip of snow from the roof seemed to occur, as 

 first thought, to most, then a colliery explosion — there are two 

 coal-beds near— and finally an earthquake. 



• The chief physical effects observed here, beside the general 

 vibration, were a violent shaking of windows, the rattling of 

 glass and crockery, such as bed-room ware. Suspended gas- 

 shades and pictures on walls swung as if with the wind. The 

 doors of rooms and cupboards opened and shut, one or two 

 ornaments fell from their brackets, and the floor is described as 

 "rising." Most of those who slept were awakened, and seemed 

 to suffer more alarm than those who had not retired. The move- 

 ments had apparently been more severely felt by them, and they 

 describe their beds as " rocking," and themselves being almost 

 thrown out. None of our telephones were affected. Substan- 

 tial buildings seemed less affected than those less solidly built. 

 The various observers quoted were all in a good position to note 

 what occurred. T. R. H. Clunn. 



The County Asylum, Prestwich. 



Can Animals count > 



Under this heading. Sir John Lubbock, in his recent interest- 

 ing book on "The Senses of Animals," gives several instances 

 of apparent counting in the case of insects. He says : — 



" One species of Eumenes supplies its young with five victims, 

 one ten, another fifteen, and one even as many as twenty-four. 

 The number is said to be constant in each species. How, then, 

 does the insect know when her task is fulfilled ? Not by the 

 cell being filled, for, if some be removed, she does not replace 

 them. ... In the genus Eumenes, the males are smaller than 

 the females. ... In some mysterious manner the mother 

 knows whether the egg will produce a male or a female grub, 

 and apportions the quantity of food accordingly. She does not 

 change the species or size of her prey ; but if the egg is male, 

 she supplies five, if female, ten, victims. Does she count ? 

 Certainly this seems very like a commencement of arithmetic." 



Now, it seems to me that this can be explained in a far simpler 

 and more probable manner than by supposing that insects have 

 any power of counting. I think we may safely consider — 



(l) That a certain average amount of food is required in each 

 case. 



{2) That a certain average time is required by the insect to 

 collect this food. 



(3) That the eggs of the insect follow one another at a certain 

 rate, over which she has little or no control. 



(4) That the eggs which are to produce males, being smaller, 

 take less time to form, and follow at shorter intervals, than do 

 those which are to produce fetnahs. 



Now take the case of the Eumenes which provides ten vic- 

 tims. She makes the cell, and goes on adding caterpillars until 

 the egg comes to maturity and is laid, and the cell finished off. 

 She then repeats the process, laying the egg when it comes to 

 maturity, as before ; the interval between the laying of one 

 egg and the next being long enough, on the average, to pro- 

 vide ten victims, or in case the egg is to produce a male, the 

 smaller interval only allows of five being provided. 



There is thus no need to credit the insect with any power of 

 counting, or of knowing beforehand anything about the sex of 

 the eggs. It is merely another instance of the perfect way in 

 which, by the process of evolution, means are adapted to ends. 



The same explanation applies to the cases mentioned on pp. 

 254-56 of " The Senses of Animals." The bee laboured to fill 

 the cell (in which a hole had been made so that the honey ran 

 out again), until, " when she had brought the usual complement 

 of honey, she laid her egg, and gravely sealed up the empty 

 cell : . . .in some mysterious manner the bee feels when she 

 has provided as much honey as her ancestors had done before 

 her, and regards her work as accomplished." 



I should suggest that the bee merely goes on bringing honey 

 until the igg is ready. She then starts another cell, and goes 

 through the same routine until the next egg is ready, and so on ; 

 the average amount of honey collected being proportional to 

 the interval between the laying of one egg and the next. Ac- 

 cording to the theory of evolution, this interval is just sufficient 

 for enough food to be provided for the use of the grub. 



G. A. Freeman. 



St. Olave's Grammar School, Southwark. 



Weight and Mass. 



Mr. Andrew Gray need only turn to p. 355 of the current 

 number of Nature to find an example of an engineer's dynamical 

 terminology, and it would tend to some useful result in this in- 

 terminable discussion if he would point out 'in what manner the 

 language of the engineer must be modified to suit the require- 

 ments of the precisionist. We find on p. 355 " the working 

 pressure is 175 pounds per square inch," "the total weight of 

 the engine in working order is 37 tons," "probably having 

 about 30 tons useful weight for adhesion," and so on. 



Let Mr. Andrew Gray point out what he considers the errors 

 of the engineers. Ought the engineer to say, " the working 

 pressure is 175 ])ounds weight (or pound weights ?} per square 

 inch," "the total mass of the engine is 37 tons," "probably 

 having about 30 tons useful (? mass or weight) for adhesion." 



On former occasions in this controversy I have attempted to 

 elicit definite expressions of opinion on the terminology of 

 similar definite actual dynamical problems, but hitherto without 

 success. A. G. Greenhill. 



Woolwich, February 12, 



Detonating Meteor. 



Mr. Maxwell Hall's letter on this subject is of consider- 

 able interest. When the great meteor-shower of November 

 II -1 5 was traced to the orbit of the comet of 1866, it was 

 natural to suppose that the fine fire-balls which occur about 

 this period belong to the same series. Plainly, however, the 

 Jamaica fire-ball recorded by Mr. Hall had a southern radiant 

 far distant from that of the well-known Leonid shower. The 

 same thing was noticed in the case of the shower of aerolites 

 which fell in France on the 13th of November, 1835, the 

 motion being south-east to north-west ; and in many other 

 instances in which fire-balls or aerolites were observed within 

 this period the phenomena seem to agree best with a southern 

 radiant, though the descriptions are not as full as we could 

 desire. It thus appears highly probable that almost concident 

 in time with the well-known Leonid shower there is another 

 shower, rich in fire-balls and aerolites, proceeding from a 

 southern radiant. I hope it will be watched from southern 

 stations in future. W. H. S. MoNCK, 



Dublin, February 15. 



