Jan. 25, 1872J 



NATURE 



241 



of the deith of 3,000 Indians from small-pox in the Saskachewan 

 district. It is then added " that martens that are not killed, and 

 Indians that die, mean reduced dividends to the Hudson's Bay 

 shareholders and traders." 



H iving lived a good many years in the Hudson's Bay Territory, 

 perhips you will permit me to mention a curious circumstance 

 which I noticed, in illustration that martens may abound yet 

 comparatively very few be killed. 



In all parts of the fur country east of the Rocky Mountains, 

 where there is timber, hires {Lcpus amcricaniis), or "rabbits," 

 as they are commonly, but wrongly, called, are found in greater 

 or less numbers, and they congregate in certain favourite localities. 

 The Indian pitches his tent near one of these places, and by 

 setting snares (which his wife and children attend to), easily 

 supplies himself and family with food, whilst the skins of the 

 hares are worked up into most comfortable blankets. 



The hunter all the while is trapping the marten and other fur- 

 bearing animals that assemble to prey upon the poor rabbits, and 

 is thus enabled to secure vfithout much labour a large and valu- 

 able stock of furs, chiefly martens. 



The hares are, however, liable to a very fatal epidemic,* 

 which usually attacks them when they have become very 

 nunierous, and they gradually die off, so that in two or three 

 years there is scarcely one to be seen. This scarcity continues 

 for a co'jple of winters or so, after which the hares again begin 

 to increase, so that at periods of eight or ten years they are at 

 their maximum. 



During this dearth of hare:, the Indian has to go to a fishery, 

 or is obliged to travel about in search of buffalo, deer, or o'.her 

 game as a means of support, and his little time for trapping the 

 marten ; and if he had the time, he would still be under great 

 disadvantage, for the marten, lynx, and fisher have also to scatter 

 themselves all o\er the country to pick up a precarious livmg on 

 lemmings, partridges, and other odds and ends, instead of feasting 

 in luxury and ease, as they do, on the hares when abundant. 

 Thus, when hares are numerous, many marten skins are obtained, 

 when hares are few marten skins are also few, not necessarily 

 because martens are scarce, but that they are difficult to get. 



The dea h of even 3,000 prairie Indians in one season, how- 

 ever injurious it might be to the trade of the Hudson's Bay Com- 

 pany in other kinds of furs, would not particularly affect the 

 number of marten skins obtained. 



I may here record a striking instance of the efficacy of vaccina- 

 tion as a preventative of small-pox. Nearly forty years ago this 

 dreadful disease spread like a scourge from the Missouri river 

 all over the prairies, being carried by bands of horsestealers 

 from one tribe to another ; for these amiable " children of nature " 

 no sooner heard of any of their neighbours being attacked by 

 the terrible disorder, than parties went immediately to rob the 

 sufferers of their mo?t valuable property. They got the horses, 

 but they also caught the disease, and many hundreds died. The 

 Crees, a tribe of many thousands, having nearly all been vacci- 

 nated by the Hudson's Bay Company's officer in charge of the 

 district, escaped with the loss of only two of their number. 



John Rae 



Ripples and Waves 



The article by Sir William Thomson upon Ripples and Waves 

 in the November part of N.\ture, which has just reached 

 me, reminds me of a little capillary wave, the examination of 

 which used to be a source of amusement to me some years ago ; 

 and as I have never seen any description of it, my observations 

 may not be without interest to some of your readers. 



I had long noticed this little wave, winding about, like a 

 hair upon the surface, amongst the eddies which formed in a deep 

 river below a consilerable fall, which I used to frequent ; but I 

 first got an insight into its nature in a very different situation. I 

 was in a canoe in a sheltered bay, with just enough wind over- 

 head, without any ripple on the water, to make my canoe drift 

 broadside on at the rate of, perhaps, halfa-mile an hour, when I 

 saw my little wave formed about three 'feet in advance of the 

 canoe. Be ng in the neighbourhood of a marsh the water was 

 very impure, and the behaviour of the little particles floating in 

 it attracted my attention. Any objects reaching to the depth of 

 from an eigith to a quarter of an inch below the surface passed 

 on to the canoe unaffected by it ; but smaller particles were sud- 



• It is quite as fatal in its effects as the grouse disease, and tlic causes are 

 Utile known The.hares are found sitting in their forms dead. The Indians 

 say they can tell when the disease isabout to commence by a peculiargrowth 

 found in the abdomen. 



denly agitated on passing the wave, and after getting a few 

 inches within it, they were arrested at distances varying with their 

 size, the larger ones penetrating farther than the smaller ones. 

 If the wind died away the wave was maintained at a greater 

 distance from the canoe, and it was still perceptible at a distance 

 of fully eight or nine feet from it, after which it became fr'g- 

 mentary and disappeared. If the pace of the canoe increased, 

 the wave came nearer to it, and the particles, which had been 

 brought to rest at various intervals according to their sizes, were 

 driven up together, forming at last a sort of scum in advance of 

 the canoe. If the wind increased sadienly, the wave disappeared, 

 and the slightest ripple on the surface obliterated it at once ; but 

 if the wind freshened very gradually, the wave approached 

 nearer and nearer, becoming at the s,ame time more strongly de- 

 fined, until it came to within about nine inches from the canoe, 

 and was maintained there under its lee, even after there was 

 breeze enough to make a considerable ripple outside. If pressed 

 beyond that, ripples of quite another character would form just 

 in advance of the wave, and it would break up, and the cinoe 

 would pass over the scum which had collected within it. 



With this clue as to its nature, I frequently eximined the wave 

 in the situations where I had first seen it. Wherever there was 

 any impediment to the stream, as a tree stretching out into it 

 frjin the bank, there was the little wave ahead of it, at distances 

 from the impediment varying with the force of the current. In 

 the spring, when the water was high, a good deal of foam would 

 be brought down from the falls above, anl would collect against 

 these obstructions, but always leaving an inch or two of cleir 

 water within the wave. Upon clearing away the foam the wave 

 would soon ajain be formed, and the next pa'ch of foam which 

 came down would experience a little jerk, as it passed the wave, 

 and penetrate a few inches within it, when it would be arrested, 

 and there would start out from underneath it little particles of 

 sawdust, or other substances, which had been entangled in it, 

 and would range themselves beyond it, in the order of their sizes. 

 Presently more foam would come down, pushing on what had 

 arrived before, till soon there would be an accumulation of it, as 

 at first. 



Where the wave was found winding about amongst the 

 eddies there was no solid obstacle, but only one stream meeting 

 another, and it was not at first sight easy to distinguish whica 

 was the front and which the back of the wave. Ttie accumulation 

 of scum, however, on one side showed this, and much more so 

 the behaviour of the wave itself, according to the side from which 

 you approached it. If you came down upon it wiih the stream, 

 with your cmoe broadside on, no effect was produced on the 

 wave; but if you passed over it, it was almost immediately re- 

 formed on the other side. But if you approached it from the 

 other side, you pushed it on before you ; and by careful handling 

 I have often succeeded in detaching a portion of the wave, and 

 carrying it on b=fore me for ten or fifteen yards ; whilst after 

 awhile another would be formed in the same place. Sometimes, 

 where the water boiled up from below, there would be an irre- 

 gular circular patch, surrounded by one of these waves, which 

 you might drive up till the two sides met ; or if you approached 

 it stern on, you would cut the circular patch into two, in which 

 case each would run up rapidly to their centre into a little conical 

 jet, and if your pace was at all rapid there would be a drop pro- 

 jected upwards from it. 



The wave is so minute that it was not easy to com; to any 

 conclusion as to its shape and size ; but from the distorted re- 

 flection of an object held above it I satisfied myself that under 

 ordinary ciicumstances it could not be more than one-twentieth 

 of an inch high, the distortion not extending beyond half-aninch 

 on each side of the sharp cusp, and that it was convex towards 

 the stream, with a very slight trace of concavity on the side of 

 the obstacle generating it. It seemed as if the wave itself was a 

 little elevated above the surface, and that it sloped back very 

 slowly towards the obstacle. This is in accordance with the 

 description above given of a narrowing circular patch running up 

 to a jet ; for, although the motion in that case was too rapid to 

 permit of any preci^e observation, just before it closed in the 

 patch had the appearance of a litt'e table land elevated above 

 the general surface. Upon one occasion, when a boom had been 

 stretched across the river, running at the time fully five or six 

 miles an hour, the wave was only ab jut nine incnes from the 

 boon, against which a dense scum was collected, but stdl with 

 about an inch of cUar waicr between it and the wave. The wave 

 in this case must hive been fully an eighth of an inch high, and 

 on its farther side were a succession of ripples, very much ex- 

 ceeding the capillary wivj in height and amplitude, and differing 



