Aug. 24, 1888.] 



SCIENTIFIC NEWS. 



(89 



It had been generally believed by the great majority of 

 Wiltshire archaeologists that Bokerley Dyke, together 

 with its fellows, " Grims Dyke," in the south of Salisbury, 

 " Old Dyke," which runs over Salisbury Plain to the 

 north of Heytesbury, and their own " Wansdyke," in 

 the immediate neighbourhood, were — whatever might 

 have been their object and whoever their authors — at 

 any rate of pre-historic date ; that, whether they were 

 the work of the early Britons, the Celts, or the Belgae, 

 they were at all events pre-Roman. But now, in remov- 

 ing a considerable portion of the bank at Bokerley Dyke, 

 and exposing the original surface on which the excavated 

 soil had been placed, General Pitt-Rivers had come upon 

 large quantities of Roman pottery and several hundred 

 Roman coins of a late date. This was evidence which, 

 however unpalatable to some of them, could not be gain- 

 said, and they might take it as proved that Bokerley Dyke, 

 which Canon James, when writing on the subject, con- 

 sidered to be the oldest of the Wiltshire dykes, and whose 

 date he attributed to some two or three centuries before 

 the Christian era, must henceforth be allowed to be of 

 late Roman, if not of earlier times. They must say all 

 honour to General Pitt-Rivers, who had set at rest for 

 ever the question of date with regard to Bokerley Dyke. 

 In conclusion, the report pointed out that a vast amount 

 of material still remained for the careful examination of 

 the members of the society in all parts of the county. 

 The committee trusted that as the older members dropped 

 off, younger and more active workers would come for- 

 ward to take their places, because they were well assured 

 that continual and prolonged efforts must be made 

 before they could claim to have in any degree mastered 

 the ancient and natural history of Wiltshire. 



In the evening the anniversary dinner of the society 

 took place at the Town Hall, after which a conversazione 

 was held, when papers were read by the Rev. Canon 

 Jackson on " Calne " ; and by the Rev. W. C. Piender- 

 leath on " Cherhill Gleanings." 



Intercepting Telegrams. — The Austrian War Office 

 is stated to be paying great attention to a matter which 

 is of the greatest importance in the use of the telegraph 

 in the field. It has been ascertained that the telephone 

 is so acute of hearing that before it every secrecy of 

 telegraphing disappears. If, formerly, it was desired to 

 ascertain the secrets of the telegraph wire the latter had 

 to be cut and an apparatus inserted. Now, with the 

 help of the telephone, all telegrams may be read easily, 

 even from a considerable distance. It is only necessary 

 to carry a telegraph wire of moderate length parallel to 

 the original line, and insert in it a telephone, from which 

 the Morse signs may be read off by ear. This would, 

 of course, be very awkward in the case of war telegrams. 

 The question has naturally arisen how this difficulty is 

 to be met. The problem is solved in a surprisingly 

 simple manner by Herr Heinrich Discher, who proposes 

 cross telegraphing for the purpose. He says that if 

 telegrams are sent from opposite directions on the same 

 wire at the same time, the listener at the telephone only 

 hears a medley of confused sounds. In practice the 

 matter may be dealt with in the following manner : — 

 One station sends actual telegrams, the other a despatch 

 previously agreed upon. As long as the operator at the 

 former station sees this despatch coming in, he may make 

 s ure that no eavesdropperis able to read the telegram he 

 is sending. — Times. 



CORRESPONDENCE. 



The Editor does not hold himself responsible for opinions expressed 

 by his correspondents, nor can he take notice of anonymous com- 

 munications. All letters must be accompanied by the name and 

 address of the writer, not necessarily for publication, but as a 

 guarantee of good faith. 



FORMATION OF ICE. 



I should like to offer for the consideration and criticism of 

 your readers the following idea as to the possible formation 

 of ice. I do not know if it has occurred to any one before, 

 and I may perhaps be saying nothing new. We know that 

 water at ordinary temperatures, say 45° F., will contract if 

 the temperature be lowered to about 39 F. This is to be 

 explained by the molecules of water being separated by 

 interspaces, as shown to exist by the experiment of dissolv- 

 ing a certain amount of powdered sugar in it, without the 

 bulk of water being increased. As soon, however, as 39 is 

 reached, or thereabouts, water begins to expand until it is 

 converted into ice at 32 . F. 



Now, whenever water freezes, it does not solidify into a 

 mass of accurately fitting crystals, like rhombs of calc-spar, 

 which have no interspaces, but always in " macles " or com- 

 pound forms, so well seen in a flake of snow ; and these 

 necessitate an abundance of interspaces. Although a block 

 of ice appears to be perfectly homogeneous, like a block of 

 transparent Iceland spar or rock crystal, yet, as Prof. 

 Tyndall showed many years ago, by transmitting a beam of 

 electric light through it, it immediately revealed its anatomical 

 structure ; it is really composed of myriads of " ice-flowers." 



Hence my idea or theory is that at 39" F. the molecules 

 of water begin to arrange themselves into lines always inter- 

 secting each other at an angle of 30°, and as soon as 32" F. 

 is reached, they become revealed to our senses as solid ice. 



This arrangement of the molecules into macles necessi- 

 tates " re-entering " angles and angular interspaces. Conse- 

 quently, bulk for bulk, a block of ice must be greater than 

 that of the body of water which composed it. 



This at the same time accounts for the decrease of the 

 specific gravity, in as much as air must constitute a certain 

 portion of the block of ice. 



As pure, transparent glacier ice is nothing but compressed 

 and consolidated snow aided by re-gelation, so, I take it, a 

 block of lake ice is of exactly the same construction, though 

 it be water directly frozen. 



Bismuth is well known to be another substance which 

 imitates ice in expanding when crystallised, and since the 

 crystals of bismuth are also compound, and incapable of 

 " fitting exactly " in the mass, a like interpretation will apply 

 to it. 



I should be glad to hear what any physicist or other reader 

 may have to say to the above. George Henslow. 



PETALS OF THE WHITE JASMINE. 

 Taking up a spray of this shrub, covered with blossom, I 

 noticed that some of the flowers had four petals each, some 

 five, and others six. I could see no indication that those 

 with four petals had lost one or more. I therefore take the 

 liberty of asking you or your readers if such variations are 

 common, and, if so, what is supposed to be the cause. 



Scrutiny. 



TENNYSON AS AN OBSERVER. 

 In your number for July 20th (p. 50) you give some in- 

 stances of an accuracy of observation on the part of Laureate 

 rarely to be met with among poets. However, cases of an 

 opposite kind are not altogether wanting. Thus we read : 



" Heavily hangs the broad sunflower 

 Over its grave in the earth so chilly ; 

 Heavily hangs the hollyhock, 

 Heavily hangs the tiger lily." 



The hanging or drooping of the sunflower, as its seeds are 

 ripening, is a well-known fact. But the hollyhock presents 

 nothing similar. 



From the first appearance of the bud to the maturity of 



