346 



♦ KNOWLEDGE ♦ 



[Dec. 7, 1883. 



only intended as a padding for the ii-on armour. The core serving 

 is invariably recovered in a wonderful state of preservation, but 

 the yarns which envelop the iron wires suffer deterioration when- 

 ever the latter become oxidised. 



The testimony with regard to the enduring qualities of vegetable 

 fibrous material is, in our opinion, so overwhelming, that we are 

 justified in believing it will be readily admitted that a cable con- 

 structed without iron wires, and with the strength-giving material 

 composed of hemp, will not possess within itself the elements of 

 decay. 



In the opinions of the authors : — 



The strength-giving material, by means of which the core can be 

 submerged and recovered, should consist of fibrous yarns or strands 

 made up in such a manner that any twisting or wiinging of the 

 fabric is prevented ; and, in order to accomplish this, we lay over 

 the insulated conductor a series of spiral or helical servings of non- 

 metallic fibres, yarns, or cords, laid alternately left and right, the 

 fibres, yarns, or cords of each serving being twisted in a direction 

 the reverse of that in which they are wound about the insulated 

 conductor. 



^ This point or feature, although at first sight a trifling considera- 

 tion, is of the utmost importance, as it constitutes the gist and 

 substance of the principle by means of which any twisting or 

 knuckling of the cable is prevented ; for it will be seen that, if the 

 yarns or cords of each serving be similar — that is to say, if they be 

 twisted in the same direction in forming them— the cable will kink, 

 notwithstanding the sei-vings be wound alternately in right and left 

 hand spirals about the core. 



A cable such as we have described would not only be more 

 dui-able than an iron-armom-ed one, but could be recovered with 

 ease and certainty from any depth. 



Strength, lightness, and durability are, we affirm, among the 

 chief requirements in a submarine cable, and these qualifications 

 are to bo found in the type which we now submit to the considera- 

 tion of this Society. 



In the discussion that followed the reading of this re- 

 markable paper, the chairman (Mr. Willoughby Smith), 

 who said the company with which he was connected had laid 

 94,000 mile.s of cable, of which Mr. Ford had superintended 

 60,000 miles, maintained the superiority of an iron sheath- 

 ing, and doubted the possibility of a hemp-sheathed cable 

 enduring the strain. 



But the authors, in reply, stated that they had had a 

 cable constructed on their pattern across Halifax harbour 

 for eighteen months, and were in every way pleased with 

 its performance. They said, furthermore, tliat they had 

 had ample evidence of the wringing action, and in reply to 

 a question put to them by Mr. W. H. Pieece, it was stated 

 that the rupture of the cables, when being picked up, in 

 variably took place u])on the bottom and at a point where no 

 tension existed, and where no other force could be conceived 

 to exist but the torsion which the authors called " wringing." 

 The production of a piece of rope known to have been 

 submerged in 1801, and only recovered three years since, 

 proved the durability of hemp. It was practically as good 

 as ever, and the only diflerence apparent was that the 

 major portion of the tar had been squeezed out. 



The result of the discussion is yet to be seen ; but there 

 is no doubt that it has awakened in the breasts of all 

 interested in the question an intense curiosity, which can 

 only be satisfied by prolonged and careful experiment. 



W. Slingo. 



NEGLECTED INSECTS. 



E. A. Butler, B.A., B.Sc. 



BUGS ! " Horrid things," you say, no doulit. But stay, 

 my friends, you are thinking only of that disgusting 

 phlebotomist, the bed-bug, the Acanthia lectidaria of the 

 learned, concemmg which there cannot be two opinions. 

 This creature, however, does not really belong to 



English soil ; it is an importation from " foreign parts " ; 

 it is, moreover, only one member, and that the most dis- 

 reputable one, of an extensive group. As it is almost the 

 only representative of that group generally known, we have 

 no other common name for its relations, and so whenever 

 the word is used, it is suggestive only of personal dis- 

 comfort and foul smells. 



I do not know that the matter is much mended if we 

 call the creatures " Hemiptera-Heteroptera," the dissimilar- 

 winged half-wings ! This is, too, sesquipedalian, and so 

 bugs I suppose they will have to remain to the end of their 

 days. The creatures are in very many cases beautiful — 

 sometimes exquisitely so; they are frequently grotesque, 

 bizarre, with some parts of their body worked up into the 

 oddest of shapes, as though Nature had experimented with 

 them, and had tried to see how far she could go in altering 

 the form of a member without altogether changing it into 

 something quite different. To all, therefore, who delight 

 in the beautiful or the curious, let me recommend the 

 study of our British bugs, of which we have over 400 

 kinds. 



They are found amongst tall grass, thistles, and nettles, 

 at roots of plants, on the foliage of oak, hazel, and other 

 trees, on furze-bushes and broom, in moss, amongst dead 

 leaves, amongst rubbish at the bottom of haystacks, on the 

 trunks of trees, on palings, in sandy places, under bark, in 

 mud at the bottom of ponds, in ditches and streams, and on 

 the surface of still water. Some of those that live in water 

 are tolerably familiar objects, and are known by such names 

 as Water Boatmen, Water Scorpions, and Water Measurers. 

 A few of the terrestrial kinds sometimes intrude themselves 

 on our notice, appearing in our streets and on our doorsteps, 

 and have received the name of Bishops' Mitres. But the 

 vast majority are scarcely ever noticed by any but those 

 who specially look for them, though they are some of our 

 most abundant insects, are around us everywhere, and may 

 be found with very little trouble. 



Excluding for the present the aquatic species, we may 

 say that the greater number readily fall under two heads, 

 which may be conveniently called hard bugs and soft bugs, 

 according as they are encased in a hard, unyielding, horny 

 skin, or have a more delicate and flexible integument. 

 They are normally four-winged insects, though in a large 

 number of cases the wings are more or less imperfectly 

 developed. One great peculiarity of the order is seen in 

 the upper wings, which, instead of being, as in most insects, 

 of uniform texture throughout, appear as if composed of 

 several pieces, like a patchwork quilt. In the hard bugs 

 there are three such pieces, two at the base of the wing, of 

 a somewhat triangular shape, the base of one triangle being 

 placed against one of the sides of the other, and of stout, 

 stiff, horny texture, and one beyond these, thin and flexible, 

 rhomboidal in shape, but with the outer angles rounded. 

 It is this peculiarity of diflierence in consistency in the dif- 

 ferent parts of the fore-wing that has suggested both the 

 names Hemiptera (half-wings) and Heteroptera (dissimilar 

 wings). In the soft bugs, in addition to the parts 

 above named, there is a small triangular piece, wedged in, 

 as it were, between the membranous part and one of the 

 basal triangles. This little wedge is sometimes of a much 

 more brilliant colour than the rest of the wing. One 

 occurs to my mind at this moment in which this wedge is 

 of a fiery red, while the greater part of the rest of the 

 insect is deep black. The hind wings are quite plain, and 

 of a very delicate membranous consistency. When the 

 insect is not flying, the hind wings are completely con- 

 cealed by the other pair, which lie along its back, over- 

 lapping one another at their outer extremity, just touching 

 in their middle, and receding from one another towards 



