2G0 



♦ KNOV/LEDG2 ♦ 



[May 4, 1883. 



■of turning its cHgo ; for I know 1iy tho extent of the 

 inodf-rn strata that it spronrls right across the face of Scot- 

 land, and proli!ilily far out into wliat is now the soa on 

 cither side. Indeed, as similar deposits arc found in Ire- 

 land, as far as the Fintono beds, I am inclined to suspect 

 tliat Lake Caledonia stretches in that direction almost as 

 far as the Atlantic coast of Ulster. Our only plan is, 

 therefore, to build a raft and sail right across it ; for this 

 is certainly the great sheet from which the lacustrine sedi- 

 mentary strata of the Scotch lowland belt between Edin- 

 burgh and Glasgow were originally derived." 



Following his advice, we built ourselves a large raft, and 

 shaped our course north-westward across this prima'val 

 Superior. After sailing from about the point where 

 Edinburgh usually stands to the centre of Perthshire, we 

 saw in front of us a long range of mountains, which we 

 recognised at once as the preeui'sors, or first rough drafts, 

 of the Grampians. These, my friend told me, must 

 represent the dividing ridge between the two main lacus- 

 trine beds of Old Red Sandstone in the Scotch Highlands, 

 aiid by crossing them, we should probably come upon the 

 largest of all the contemporary inland waters, the Lake 

 Orcadie of Professor Geikie. We therefore pushed our 

 way through the dense jungle in a northerly direction, and 

 from one of the highest summits in the range, we 

 caught a glimpse on the left of another considerable 

 inland sheet, which we felt sure was Geikie's Lake 

 Lome, occupying the basin now marked by the 

 terraced volcanic hills of North- Western Argyllshire. 

 Descending from the ridge, we soon found ourselves 

 on the wide shores of Lake Orcadie itself, an immense 

 .stretch of open water, indented into numerous bays, and 

 bounded on the near side by a range of high hills on the 

 site of Ross and Sutherland. How far it spread away to 

 the north-east, over the modern bed of tho German Ocean, 

 towards Norway, wo could not quite make out ; but we 

 knew it was fully big enough to have left its sediment 

 along the whole shores of the Moray Frith, across the 

 corner of Caithness, and onward as far at least as the 

 Orkneys and the southern outliers of the Shetland group. 

 We felt it would be quite impossible for any raft to live in 

 such an inland sea as that, and so we halted here as the 

 final end of our excursion, being deterred from proceeding 

 further partly by fear of danger, and partly by our 

 ignorance of the deposits underlying the Atlantic and the 

 German Ocean, which prevented us from obtaining a trust- 

 wortliy chart of the regions now covered by their beds. 



The Snow Plough in India. — The snow plough has 

 l)een used on an Indian railway this winter for the first 

 time. At Darjeeling, on January JO, so heavy a fall of 

 snow took place, that the train could not proceed until a 

 plough had been fixed to the engine. At Naini Tal, from 

 .January 24 to January 28, the snow and rain rendered 

 the station almost inaccessible, and caused great difficulty 

 in forwarding the mails. — Enyineeriiii/, 



A NON-INFLAMMAULE InSULATIXC MATERIAL. MeSSrS. 



W. A. <k S. E. Phillips have taken out a patent for an 

 improved method of making the insulating bodies of 

 electric light conducting wires non-inflammable. The in- 

 vention consists in passing tho wires, covered or uncovered, 

 through a solution of tungstate of soda. According to 

 another part of the invention a concentrated aqueous 

 solution of tungstate of soda is prepared and poured into 

 boiled linseed oil, which is heated and kept stirred until 

 the water has evaporated. A portion of this fluid is then 

 mixed with the insulating compound used to cover the 

 M'ire. 



"OUR BODIES:" 



SHORT PAPERS ON PHYSIOLOGY. 



By Da Andrew Wilson, F.R.S.E., Ac. 



No. XI.— THE CinCULATIOX OF THE BLOOD. 



THAT blood circulates perpetually tlirough our bodie.s, 

 is, of course, one of the acknowledged truisms of our 

 physical life. So tacitly, however, is the fact taken for 

 granted, that very few persons seem to trouble themselves 

 further regarding the mechanism which keeps this per- 

 petual flow in motion. Possibly the most salient features 

 of the blood-circulation consist in the knowledge that the 

 Jtearl, by its incessant movement,'is charged with the duty 

 of sending blood through the body ; and that the blood, 

 secondly, flows, or is thus driven, through certain pipes or 

 bloodvessi'/ti. The heart in this light is a kind of force pump ; 

 and if we add that it is a muscular force-pump, we shall 

 have found a rough and ready, but essentially correct, idea of 

 the nature of the heart As a hollow nuisclr, the heart no 

 longer appears as a mysterious organ. It is hollow, to 

 allow blood to pass through it; it is a muscle (or rather 

 collection of muscles), that it may propel the blood through 

 the body by its forcible contractions. For, after all, the 

 same force by means of which we write a letter, or move 

 our legs in walking, is that which drives blood through 

 our bodies. The muscles of our fingers and arm contract 

 when we write ; the heart's muscular substance, in the same 

 way, contracts when the heart "beats." The description of 

 a heart as a "hollow muscle" is one also which applies 

 with equal force to all hearts ; and the heart of an insect 

 or the pulsatile organ of a snail or oyster as fully conforms 

 to this definition as that of a man. 



We have already seen that the blood in the course of its 

 circulation exists under a double phase. It goes forth from 

 one side (the left) of the heart and from the lungs to nourish 

 the body. It is then pure blood ; it travels through pipes 

 or tubes called arteries, and hence it is often spoken of as 

 arterial blood. If we trace any arterial bloodvessel 

 through its ramifications, we may see that it divides and 

 subdivides, and finally spreads out into a network of fine, 

 delicate-walled vessels, known as the capillaries.] So 

 minute are these capillaries that, as a rule, they will 

 allow only a single row of red blood corpuscles to 

 pass along their interior at one time, like soldiers 

 in single file. The diameter of these capillaries 

 is, therefore, about the one three - thousandth of an 

 inch. We can readUy see that as the tissues of our 

 frames are permeated by such a dense network of blood- 

 vessels, they must receive not only a very large and 

 constant supply of blood, but must have that fluid like- 

 wise brought into connection with the most minute parts 

 or " cells." The fluid part of the blood strains through 

 the capillary walls, and thus bathes the tissues in nutri- 

 ment ; and it is this fluid part of the blood which, in turn, 

 is taken up by the absorbent vessels, as described in a 

 former paper. 



We may further observe that at no part of the circula- 

 tion do the bloodvessels end abruptly, or like a street with- 

 out openings. On the contrary, the special feature of the 

 circulation is, that it is carried on in a set of closed tubes, 

 which are everywhere continuous. If blood escapes from 

 any bloodvessel at all, it must do so either naturally, that 

 is, by straining through its walls, as already described ; or 

 it must escape through injury to the vessel. A wound of 

 any bloodvessel, small or large, is thus really an opening 

 into a system of close and continuous pipes. 



The blood, then, which the arteries have carried to 



