Chapter VII: Part 7

As I had been so fortunate in observing the Lampreys, I felt desirous of ascertaining whether the same thing could be seen in other fish (as in Natural History it is not always safe to reason from analogy), and as there was a large shoal of Minnows spawning near the place where I had seen the Lampreys, I determined to watch their motions. They happened to have chosen a very convenient place for being observed, being between two large stones in the river, which lay about three feet from each other; so that by cautiously approaching them from behind one of the stones, I got close to without disturbing them, but after watching them carefully and repeatedly within the distance of two feet, I can only speak doubtfully of their operations, for they were so numerous, and their motions were so incessant; and when a female was about to shed her spawn, the males (which were ten times more numerous than the females) crowded round her in such a manner as to render it very difficult, if not impossible, to speak with certainty on the subject. I will state what steps I took to satisfy myself, and perhaps the history of my failure may be of use to future observers.

It occurred to me from what I observed, that it was probable the males had the power of absorbing the eggs after their exclusion by the female, and impregnating them within their own bodies; and I caught a dozen males at different times, when they were attending on females, and opened them, but I could discover nothing like an egg. I then caught a female, and scattered the spawn (which was expelled by the slightest pressure) in a place frequented by a number of males, but they took no notice of it whatever. I after this caught a female when she was surrounded by a number of males, and apparently in the act of shedding her spawn, and examined whether the spawn which I pressed from her body was impregnated; but it appeared perfectly homogeneous, and so delicate in its texture that it burst with the slightest touch, whilst in that which I picked up from among the gravel where it was scattered abundantly, the impregnation was visible with the assistance of a microscope, and it was so much tougher in its covering as to bear rolling about in my hand without injury. I then tried to impregnate the eggs _mechanically_, and applied a drop of the spermatic fluid to the egg at the moment of exclusion, and it certainly seemed, in one instance, both to increase the size and to alter the colour of the ova it was applied to; but I was not able to produce the same effect so decidedly in any of my subsequent attempts.

My observations, which were often repeated, induce me to believe that the egg is impregnated at the moment of exclusion, and that two males have (almost invariably) access to the female at the same time; for I frequently remarked, that when a female came among a number of males, they immediately pursued her: if she was not ready for shedding her spawn, she made a precipitate retreat; but if she was, she came boldly in among them, and was immediately pressed closely by a male on each side, who when they had been in that situation a short time, were superseded by other two, who wedged themselves in between them and the female, who appeared to treat all her lovers with the same kindness.

One difficulty is, that the spermatic fluid mixes very readily with water; and I cannot imagine how its virtue is preserved, [14] if (as I suppose must be the case) the egg is impregnated after exclusion; but I also think it probable that the ventral fins of the female serve to conduct this fluid to the place where it is needed, and the chemical affinity between it and the egg may be sufficient for impregnation.

P.S. July 27th. I tried to hatch some of the eggs I had endeavoured to fecundate. The attempt was unsuccessful. I placed the eggs, which I had put into some clean-washed gravel, in a shallow vessel (open at the top, and with holes drilled through the sides) in a small stream of water, but I found to my great mortification on looking for them a day or two after that there was not one left, but that in their stead were many aquatic insects, which had no doubt feasted on them as long as they lasted, and after this I was not able to meet with another shoal of Minnows in the act of spawning.

The head of the Minnow in the spawning season is spotted over with small white knobs, apparently osseous in their structure, which make their appearance immediately before the fish begins to spawn, and which disappear again as shortly after, and I think they are intended as a protection to the head of the fish during the spawning; as I remarked that they generally thrust their heads in between two pebbles, and had their tails sticking up almost perpendicularly. Yet this was not always the case, as they sometimes ran nearly out of the water, and it was in this situation that I observed what I have before mentioned, as I found it impossible to discover anything that was done by those in deeper water; for when a female went into such a situation, there was such a crowd of males rushed to the place that I lost sight of her in a moment.

I was astonished to find how quickly the eggs were hatched. I discovered a large shoal spawning on the 11th of May; on the 12th they were diminished to one-tenth of the number, and on the 14th (the 13th being Sunday) there was not one left. As I had by no means satisfied myself on the subject, I felt disappointed that they had so soon finished their operations, and I took up a handful of the gravel where they had been spawning, and examined it with the microscope, to see whether I could discover any ova, and how they were going on, when to my great surprise I found them already hatching and some of them already excluded from the egg. One of them, which I took on the point of a knife, swam briskly away, and another was the means of pointing out an enemy to me which I had not previously suspected, and that I had always hitherto believed to be the prey of and not the preyer upon fish. The poor Minnow had somehow got fast to the point of the knife, and in its struggles to free itself it attracted the attention of a creeper--the larva of one of the aquatic flies called drakes (_Ephemerae_)--which pounced upon it as fiercely as the water staphylinus does on the luckless tadpole, but, fortunately for the Minnow, either the glittering of the knife-blade or the motion of my hand, scared it away again without its prey.

The young Minnows in this state were quite transparent, except the eyes, which were disproportionately large; and they seemed to be perfectly aware that they owed their safety to concealment, as those that I saw immediately buried themselves in the gravel when they were set at liberty. (July 27th, 1832.)

* * * * *

EELS.

To the Editor of the "Gardener's Chronicle."

My attention has been called to a paragraph in a Worcester paper giving an account of a (so-called) discovery by Mr. Boccius, that Eels are propagated by spawn, like other fish, and that they are not brought forth alive, as had hitherto been supposed. This may be true, but before I can give an unqualified belief to the assertion, I should like to have a few questions answered by Mr. Boccius. Who saw the fish from which those thousands of eggs were extracted at the time this dissection was made? Are the parties who saw these eggs quite certain that the fish was an Eel and not a Lamprey? Who saw the eggs from which Mr. Boccius produced living Eels? Who beside Mr. Boccius ever saw Eel-fry in a pond which had no communication with a river? Will Mr. Allees and Mr. Reed (the gentlemen to whom the spawn was exhibited) say whether the ovary which was shown to them was pretty much of the same form as that of the Lamprey? and if not, in what respect did it differ?

I am induced to ask these questions, both because by inference they show my own opinions on the subject, and because I am led on undoubted authority to believe that Mr. Boccius is inclined to claim at _least_ all that belongs to him; and also because I have my doubts about the scientific attainments of Mr. Boccius in the Natural History of Fishes.

It is difficult to prove a negative. My never having seen the strange things above mentioned certainly does not prove that other people with better eyes and more discrimination have likewise failed to do so; but I can't help doubting, and I publish my doubts in the hope that the subject may be further inquired into. A true naturalist ought only to wish for the truth, without reference to his own preconceived notions; but so far as my examinations have gone, I have failed altogether to detect spawn in the fringes which I have fancied were the ovaria of the fish, or elsewhere, and I don't believe that Eels are bred in fresh water at all. I see the fry ascending from the sea in May and June by thousands and millions, but I never met with one of these in a pond having no communication with a river. I have little doubt that I shall be pronounced in error touching this matter, except perhaps by those who know how perseveringly these little Eels make their way up every stream, ditch, and driblet of water into which they can gain access. They penetrate into the water-pipes and pumps; they climb up the perpendicular faces of the rocks and weirs which obstruct the course of the rivers, even when they are only moist--adhering to the moss and stones like snails.

The downward migration of Eels is observed here from July to the middle of September, but in the Manchester market I find them up to this time (the end of November), and am informed that they are caught at the foot of Windermere in their downward migration.

Would a dissection of the Conger at various seasons throw any light on the propagation of Eels? One would think that in such large fish the ovaria would be much more easily distinguished than in smaller specimens. (November, 1850.)

_The above elicited the following reply:_--

T. G. denies the possibility of Eels breeding in fresh water. We have a pond here covering three or four acres which swarms with Eels of all sizes. I have caught them from the size of my little finger up to the weight of five pounds. The supply of water is from nothing else than land springs--there being no communication between the pond and any river. When much rain occurs I am obliged to put up a sluice-board, in order to prevent the banks from overflowing. I have taken from one to two hundredweight at a time from a box which the water flows through at the bottom of the sluice-board. The large quantity that has been taken out of this pond leaves no doubt that they breed there to a great extent, but whether they are propagated by spawn or brought forth alive I am unable to say.--G. H., _Finedon Hall_.

_Reply to the foregoing._

Your correspondent G. H. says T. G. denies the possibility of Eels breeding in fresh water. This is rather too strong. I don't deny the _possibility_ of Eels being bred in fresh water, I only deny the _probability_. The expression I used was that I did not believe they were bred in fresh water at all, and I distinctly stated that my not having seen these things (Eel spawn, &c.), did not prove that other people had not done so. But to the question. G. H. says that he has caught them of all sizes, from the thickness of his little finger to five pounds weight. No doubt he may have done so, but did he catch them of the thickness of a crow's quill, and three inches long? because that is the size at which they usually ascend rivers. He says his pond does not communicate with any river. Is there no escape of water from it? I mean, is the evaporation from its surface equal to the supply of water? If not, where does the surplus go to? Does it not directly or indirectly flow into a river or the sea? I am the more inclined to think that this is the case, because G. H. says he caught a hundredweight at a time from a box which the water flows through at the bottom of the sluice-board. This is exceedingly like what is done here and elsewhere from July to the end of November, when the Eels are on their downward migration. Will G. H. be kind enough to say whether he does not catch his about the same time? will he also say whether the Eels he catches are not Silver Eels? and will he also state whether he does not catch them principally after heavy rains have increased the flow of water out of the pond? If he answers these questions in the affirmative, I shall still think I am right, and request him to keep a sharp look-out after rains in May and June, when I think he would probably see the grigs passing through his box into the pond. If, on the other hand, there is no escape of water from the pond at any time, I must admit that I am wrong, but at present I don't know how to reconcile the impounding the water so completely with what he says about the flow of the water through the box at the bottom of the sill. Where does the water flow to, and for what is this sill?

_G. H. replied as follows._

T. G. asks if I have caught Eels of the size of a crow's quill. I have caught them of the size of a tobacco-pipe, and from three to four inches in length.

Our surplus water flows indirectly into the river Nene from our sluice. It supplies some stews where we have been in the habit of keeping reserve fish, and passing over several waterfalls, it enters into a ditch which is about three-quarters of a mile long, and then reaches the river I have just named.

The greatest take of Eels I have had was on the 23rd of December, but the time of the year is of little consequence with us, provided the water is thick and muddy and the weather rather warm, which, of course, only occurs during very heavy rains. If I were to draw all the water out of the pond when in a clear state, I should not catch a fish. The variety is the Silver Eel. Our pond is upwards of fifty miles from the sea; therefore how is it that those little Eels had got no larger during their long journey, interrupted as it is by numerous and almost insurmountable obstacles, before they could reach the little ditch, three- quarters of a mile long, that would conduct them to our pond? And, last of all, after this long and tedious journey, within a hundred yards of their destination they would have to climb four waterfalls and a perpendicular sluice-board. It appears to me they should have grown much larger than a common tobacco-pipe and longer than three or four inches in that time, but I will leave this point for T. G. to explain.--G. H., _Finedon Hall_.

_Reply to the foregoing._

Many thanks to G. H. for his second letter on this subject. It appears to me that we think very much alike about Eels.

He says his pond is fifty miles from the sea; "therefore, how is it that these little Eels get no larger in their long and tedious journey? interrupted as it is by numerous and almost insurmountable obstacles, before they could reach the little ditch, three-quarters of a mile long, which would conduct them to our pond? and last of all, after this long and tedious journey, within a hundred yards of their destination, they would have to climb four waterfalls and a perpendicular sluice-board. It appears to me they should have grown much larger than a common tobacco-pipe during that time; but I will leave that point to T. G. to explain."

This is so fairly put, that I will tell what I have seen, hoping that this will be a sufficient explanation.

In June, 1850, I chanced to go down to the bank of the Ribble, and there I saw a column of small Eels steadily making their way up the stream. I should suppose there might be fifty in every lineal yard, for they kept pretty close to the bank, apparently because they met with less resistance from the stream, and without pretending to accuracy I supposed they travelled at the rate of a mile an hour. This was about five o'clock in the afternoon, and I went to look for them about nine in the evening--they were still going in one unbroken column. How long they had been going when I first saw them, and how long they continued to go after my second visit, I don't know, but many thousands--perhaps millions--must have passed that day. At this rate (of a mile an hour) they would have required little more than two days to reach G. H.'s pond, fifty miles from the sea; but he says they had to pass over three or four waterfalls and a perpendicular sluice-board. If these waterfalls and the sluice-board were covered with moss, they would climb them as readily as a cat does a ladder. I have seen them in swarms at a perpendicular weir here, winding their way through the damp moss with which the stones are covered; but this was not all: where there was no moss, the little things seemed to have the power of adhering to the perpendicular face of the stones, like so many snails. I must not omit to remark, that although they seemed to choose the margin of the stream for the sake of easier travelling, yet they took care to keep in the stream, as I had a nice opportunity of observing.

At the point where I first saw them, the tail goit of a water- wheel had its junction with the river, but being Sunday there was no current there--not a single Eel took its course up the goit, although the water was deeper there than where they went. The water being low and perfectly clear, I could trace their course both above and below the place where I stood without any difficulty.

If we allowed that they travelled a mile in the hour, and that the obstructions of the waterfalls and sluice-board took as long to get over as all the rest of the journey, they would be able to reach G. H.'s pond in four days from the sea; and from what I have seen of their ability to surmount such obstructions, I am quite convinced that they would travel that distance in the time. But say they were a week--they would not grow much in that time, particularly if they had been travelling without food the whole of the distance, and that they must have done so, is proved to my mind by their keeping in column; for if they had dispersed to seek for food, by what contrivance were they marshalled into line again, to enable them to proceed? Now the place I saw them is forty miles from the sea, although not that distance from salt- water. T. says it is no proof that Eels are bred in fresh water because they may be found in ponds having no connection with a river--the proof required is _ab ovo_. If we wait for this proof I fear we will have to wait for some time, for I fancy that no one but Mr. Boccius ever saw the ova of Eels, and he will not condescend to enlighten us on the subject. At the same time I admit that finding them there is no proof that they were bred there, inasmuch as I have myself stocked such ponds for my friends, and what I have done may be done by others.

T. says further there is also room for inquiry into another curious subject--do Eels return to fresh water after having gone to the sea for spawning? In reply to this, I can only say, that no trace of such a migration is ever seen here, and I think if it existed at all, I should have observed it, for the following reasons.

The Ribble here supplies a large mill, the water-wheels of which are 150 horse-power; therefore, when they are at work in the daytime, the whole force of the river is often passing through the mill-lead (goit) and the bed of the river between the weir, and the tail goit in such times is left dry, except in a few pools. If there was a shoal of Eels between these two points it would have been seen at one time or another, and this has never happened, so far as I know. It may be said that they migrate singly, but they don't do so in their first migration, and, so far as I am aware, it is not the habit of any animal to do so. Herrings, Pilchards, Smelts, Flounders, Sturgeon, Bisons, Antelopes, Woodcocks, Swallows, Fieldfares, Locusts, and even Butterflies congregate together previous to migration.

NOTE.--The last paragraph requires some modification, as I have since proved that Eels migrate singly when going to the sea, as I have had occasion to know in a hundred cases when watching my Eel- trap, where every Eel may be seen as it descends into the trap.

_On the same subject._

I [Jeremiah Garnett, brother of the writer, and editor of the "Manchester Guardian,"] having noticed the communications on this subject which have recently appeared in your columns, am desirous of mentioning a fact which appears to me to throw some light upon the localities in which Eels are bred, though it leaves the question of the mode of generation precisely where it stood before.

Like your correspondent T. G., I have many times seen columns of small Eels ascending the Ribble and other rivers in the months of May and June, at considerable distances from the sea, but only on one occasion have I seen them under circumstances which evidently brought them near the place of their nativity.

I happened to be attending the Lancaster Spring Assizes in the month of March in the year 1826, and learning that there was a remarkably high tide in the estuary of the Lune, I walked down to the riverside about the time of high water, and found that the tide had covered the grass in many places; and as it began to ebb, I observed something moving in every small hollow which had been overflowed, and in which a little water had been left behind. On examination I found that the moving bodies were exceedingly diminutive Eels, rather less, to the best of my recollection, than three-quarters of an inch long, and almost transparent, but exhibiting in every respect the true form of the mature Eel. They had evidently followed the water to its extreme verge, where it could not have been more than an inch deep, and that they must have been very numerous was clear from the large numbers which were left behind and had perished--for that they did perish I found on the following day, when they were lying dead on the grass by hundreds. Some of your correspondents who reside in localities favourable for making observations on this subject may be induced to pay attention to it; the exact appearance may be ascertained, with probably other facts calculated to throw light on the obscure question of their generation.

* * * * *

ON THE POSSIBILITY OF INTRODUCING SALMON INTO NEW ZEALAND AND AUSTRALIA.

_October_, 1859.

The colonists of Australia, Tasmania, and New Zealand appear to wish for the introduction of Salmon and Trout into the rivers of these colonies, and one of them, Tasmania, is said to have offered the reward of L500 for the first pair of live Salmon which reaches that colony. If this is true it is a liberal offer, and one that is likely to induce various persons, both in England and France, to make the attempt.

I should be sorry to say anything to check so laudable an endeavour, but I greatly fear that Van Diemen's Land (to say nothing of the Australian colonies) is too near the tropics to offer a reasonable chance of success. I think it is practicable to take these fish there (or at least fertilized ova), but I don't think they would live and thrive in the rivers of that colony. Never having been there, I can, of course, only reason from European experience, but the best inquiries I can make lead me to suppose that there are no Salmon in France (south of Brittany), Spain, or any of the countries washed by the Mediterranean Sea; and in America (although I confess I am not so well informed on that country) I have never heard of Salmon being seen to the south of the tributaries of the St. Lawrence. Supposing this to be so, I think that we may fairly infer that if Salmon are not found south of a certain latitude in Europe and America, it must be that the climate of these southern countries is not congenial to the habits of this fish. I believe, however, that the Trout lives and thrives much further south than the Salmon; for instance, it is found in the Pyrenees and in the lakes of Northern Italy (Lady M. W. Montagu). It is also found in Northern Turkey, and probably Albania also (Spencer); and therefore I think it is quite probable that it might live in Tasmania--that is, if the streams are never dried up and the rivers reduced to a number of water-holes, which appears to be the case in Australia. Should this be the case in Tasmania also, I doubt whether even Trout would thrive, for here in Lancashire I have known the Trout to die in great numbers from the heat, when, owing to the water-wheels of the mill diverting the river from its usual channel, there was no stream, but merely a series of detached pools or water-holes; and the Grayling seem to be more incommoded by heat than the Trout, and it was one of the diversions of my boyhood to wait until the wheels of my father's mill were stopped in the hot weather, and then go up the covered wheel-races in search of the Grayling that had gone there to get out of the sunshine. I used to catch them there in great numbers. However, this has nothing to do with the matter, except to suggest that although Grayling are very desirable fish to introduce into the colonies, I fear they would be too impatient of heat to thrive there. But my object in addressing you is to ask whether it is true that the legislature of Tasmania has offered the prize of L500 for the first pair of live Salmon taken there?

Secondly, whether they offer a prize for the introduction of Salmon fry; and if so, what is the amount offered?

Thirdly, whether they offer a prize for the introduction of fertilized ova of Salmon or Trout, and what is the amount?

I ask these questions because I happen to know a good deal on such matters, and I have been applied to this day by James Birch, the head water-bailiff of our river (Ribble), to obtain some information for him on the subject, as he seems seriously bent on making the experiment, provided the reward be an adequate one; for, to be successful, it would involve the necessity of his making the voyage himself, and it would be a cruel thing to induce him to do so, and in the end to find that he was entitled to no reward.

I'll say this for him, that if he tries he will succeed, if success be possible; but his pecuniary resources are too limited for him to undertake such a risk.

I have reason to believe that he has been applied to by Ramsbottom to go to Tasmania, but this he declines to do under Ramsbottom's auspices. As he (R.) professes to be in communication with the authorities of Tasmania (or at all events with influential persons there) let him make the first attempt, and if he succeed, there will be no necessity to apply to me on the subject; but if he should fail--as I think he will--why, then the persons interested in the matter may, if they wish to try again, let me know their wishes and the amount of remuneration they mean to give.

I should certainly suggest that both Salmon and Salmon Trout (as well as the common Trout) should be included in their list of desiderata, and although for reasons previously given I have no great hopes of success with the two former, I think it quite probable that the common Trout would succeed better. Of course I know nothing of the fish already in the rivers of Tasmania; for aught I know there may be fish in all those rivers quite as voracious and destructive as the Pike are here. If this is the case, the chances of success would be materially lessened, as Trout and Salmon fry are rare in all rivers stocked with Pike. However, those who are making the attempt ought to know what they are about, and will, no doubt, have considered such obstacles, if there are any such in the way. Will you, therefore, be kind enough to answer the questions I have asked above, at your earliest convenience, and if your replies offer any inducement to Birch to make the attempt, I have no doubt that he will be quite ready to do so.

For various reasons he can only start from here in the autumn or winter, and he should, if he reaches Tasmania with either live fish or fertilized ova, have someone to render him prompt and cordial assistance to enable him to deposit the fish or ova, or fish and ova, in suitable places for spawning and hatching; and therefore if this letter be replied to, the answer ought to say to whom Birch should apply on his arrival in Tasmania.

It may be asked, who is the man who obtrudes his opinions on the colony unasked, and what can be his motives? As I am not aware that I know a single person in Tasmania, I cannot refer to anyone there; but I happen to know one or two gentlemen in Melbourne, and if you will take the trouble to refer there to Messrs. W. and B. Hick, or to W. Bailey, the corn merchant, they will be able to satisfy all inquiries.

If it be asked what I know of the habits of fish, and Salmon in particular, I beg to refer the inquirers to Loudon's "Magazine of Natural History" for 1834 (if there is a copy of that work in the colony), and they will there find two papers (signed "T.G.," Clitheroe) which will show that I then knew all that has since been proved by the elaborate experiments made at Perth by Ramsbottom, and moreover I taught Ramsbottom himself the art of propagating fish artificially.

I want no compensation: the honour of being the first man who succeeded in introducing these valuable fish into the colonies would be a sufficient reward to me. But with Birch the case is different: he is a working man, and L500 would be a fortune to him. On the other hand, he could not afford to come to Hobart Town from England at his own expense, as he has not the means.

Would the colony, if other attempts failed, be willing to pay Birch's passage out and home if he failed also, and would he receive the L500 if he succeeded?

By success I mean that he would either bring live fish or ova that would hatch into live fish. Either of these objects being accomplished, he ought, in my opinion, to receive the reward; for although he would attempt both, he would probably fail in the former.

Should he attempt this under my advice, I should not only send Salmon and Salmon Trout and their ova, but the common brown Trout and its ova also, for the reason previously given in this letter; and although I am by no means sanguine of success, on account of the temperature, the experiment is too important to be abandoned for a mere theoretical objection which may be erroneous.

I think New Zealand offers far greater chances of success. It is not only further removed from the tropics, but, if I am rightly informed, the streams are more abundant and constant than those of Australia and Tasmania--in fact, I believe it is as well watered as this country; and if the authorities there are as much alive to the importance of introducing these fish into their rivers, I would undertake to do this with much greater confidence of ultimate success than I should have if I undertook to introduce them into Tasmania or the sister colonies.

Some time since (it may be eighteen months or two years ago) there was a very intelligent correspondent of the "Field" newspaper, whose _nom de plume_ was the Maori one, "Wetariki no te wai Herekeke," or a similar one; and I having written something in the "Field" on this subject, the New Zealander asked for my address, which, for some private reason of his own, the Editor declined to give until so long a time had elapsed that Wetariki Herekeke had returned to the colony--this I learnt from an indirect source-- otherwise I should have tried to induce him to undertake the experiment of introducing all the various species of the genus Salmo which are to be found in our rivers.

If the colonists of New Zealand wish to make the attempt, I shall be most happy to render them all the assistance in my power, and I know no one so qualified as Birch to undertake the management of such an experiment; for he is exceedingly intelligent, has a perfect knowledge of the habits of both Trout and Salmon, and thoroughly understands the feeding of fish, both in their natural haunts and artificially, and would consequently be able to select suitable localities for conducting such an experiment to a successful issue.

NOTE.--No reply was given to this by the authorities of Tasmania, but a similar communication, addressed to the Governor of New Zealand, elicited a very polite reply from his secretary, in which he said that there were no funds available for such a purpose, but that the subject would be brought before the legislature on their assembling, and would no doubt meet with their favourable consideration; but the Maori troubles broke out immediately after, and I heard no more about it.

* * * * *

CLITHEROE, _October 14th_, 1859.

To the Editor of the "Field."

In the "Field" of some weeks since, it was stated that the colonists of Tasmania were offering a large reward for the introduction of live Salmon, Salmon fry, or the fertilized ova of Salmon.

Will you have the kindness to say what was the amount offered? who were the parties who made themselves responsible for the payment? and what time did they give within which they would pay for a successful attempt?

I am the more anxious to have this information, because I have been applied to for advice by an exceedingly likely person, as the reward (L500) which he understood to be offered is to him so tempting a sum, that he would need very little encouragement to undertake the management of the experiment; and from what I know of him I will venture to assert that he will succeed, if success be practicable.

But before I speak confidently of success, I would like a little more information, and will thank any of your readers who are able to do so, to give me replies to the following questions:--

Are there any Salmon in the rivers of Spain, or in France, south of the Loire, or even in that river? If not, why not?

Are there any Salmon in North America, in any river (not a tributary of the St. Lawrence), south of that river? If there are, what rivers in the States contain Salmon.

Do any of the rivers on the west coast of America below the latitude of 40 degrees N. contain Salmon?

Do any of the rivers of China (not Chinese Tartary) contain Salmon?

If I am right in supposing that the rivers I have pointed out have no Salmon in them, is it not exceedingly probable that the high temperature of these southern countries is unsuited to the habits and uncongenial to the health of these fish? Or how is it when they are on the same seaboard further north, they don't ascend these rivers, unless there are some such objections to their doing so? And if these objections really exist, then do they not equally exist in the rivers of Australia and Tasmania?

But there may be other objections equally fatal: there may be fish in their rivers as voracious and destructive as our Pike; there may be Sharks and other fish in their seas and estuaries, which would snap up every Salmon that entered them. There may be Seals, Porpoises, Albatrosses, Man-of-War birds, and Cormorants, as well as fifty other nameless enemies, all combining their efforts to defeat so desirable a consummation; and, after all, there may be no one willing to make himself responsible for a repayment of the necessary expenses, for corporations and public bodies are proverbially untrustworthy.

Yet, notwithstanding all these doubts of success, I think the experiment ought to be made; for its success would confer so great a boon on the colony in which it was made, that they (the colonists) ought to incur considerable risk and outlay for the chance of success, however small. I don't think there will be much difficulty in carrying fertilized ova there, but when hatched I fear they would not thrive.

I think New Zealand offers far better chances of success: it is further from the tropics, it abounds in suitable rivers, the climate and temperature are more like England, and I believe the rivers never degenerate into mere water-holes, as they seem to do in Australia; and I think the residents of that colony ought to make a vigorous attempt to introduce Salmon, Salmon Trout, and the common brown Trout into their rivers immediately; and I should be delighted to render all the assistance in my power to accomplish so desirable an object.

* * * * *

ON THE FORMATION OF ICE AT THE BOTTOM OF RIVERS.

_Anchor Frosts._

A correspondent of the "Magazine of Natural History," in endeavouring to explain the causes why water freezes at the bottom in rapid streams, says this unusual phenomenon may be rationally accounted for by anyone who has attended to it; that the streams in which anchor frosts occur generally are those which contain water of different temperatures--viz., surface-drainage and land springs and main springs, the first being always colder than the latter, in winter these never being less than 40 degrees, even in severe frosts.

These colder globules being first frozen, float on the surface of the water individually, being prevented from coalescing by the intermediate main-spring-water, and where the water passes in a shallow stream over the pebbles the crystals are intercepted by the interstices of the stones, and then become heaped together in thick beds.

The fact of the crystals of ice (which are specifically lighter than the water) sinking below the surface, is a circumstance requiring explanation. They do not sink from their specific gravity, but in the commotion of the current they are occasionally submerged, and while so are stopped by any obstruction, when they commence and compose the aggregation.

Thinking this was an erroneous view of the matter, I replied as follows:--

J. M., in his remarks on anchor frosts, appears to me to have fallen into several errors in endeavouring to account for them (they are called bottom frosts in Yorkshire); for, admitting that main springs are of the temperature stated (40 degrees) when they issue from the earth, I am by no means prepared to believe that they keep that temperature long, or that the water issuing from them does not mingle intimately and immediately with the water of the river into which it flows; especially in the situations where anchor frosts are most common, which are rough and rapid streams.

From J. M.'s statement it would appear that globules of water of different temperatures mix together without the one imparting its excess of caloric to the other, which is contrary to the experience of everyone; it is true, that in still places there will be different temperatures in the same body of water, but it is not owing to the main springs of which J. M. speaks, but to the peculiar way in which water is affected by cold. It is well known that water increases in density down to 40 degrees, below which temperature it begins to expand, and this expansion continues until it reaches the freezing-point, so that in severe frosts there will be strata of different temperatures from 32 degrees to 40 degrees. Again, he says that "the crystals of ice are intercepted by the interstices of the stones, and then become heaped together in thick beds;" but if my observations are correct, these depositions begin first round the large stones, which are not likely to stop small spiculae any more than are the water-gates of mills, where, he says, the accumulations also take place.

Anchor frosts are most common in the rapid streams occurring below deeps in rivers, and I have seen a weir on the river Wharfe which had a wall of ice four feet high formed upon it in a single night by a sharp north wind. In my opinion a sufficient explanation of this freezing at the bottom of rivers is to be found in the fact that water when kept still may be cooled down below the freezing- point without being congealed; but if the vessel in which it is kept be shaken, a portion of it will be converted into a porous, spongy ice, and the temperature immediately rises to 32 degrees. In the deeps of rivers the same cooling below the freezing-point takes place without congelation, but as soon as this water reaches the stream below, the agitation immediately converts a portion of it into ice, which collects round the large stones at the bottom in the same way that crystallization commences in a solution of salt or sugar around a piece of thread or other substance which may be suspended in it. If a severe frost is followed by a bright day, thousands of these detached pieces of spongy ice may be seen rising from the stones which have served as nuclei for them; which proves that the detention of them is not merely mechanical, but that precipitation (if I may be allowed to call it so) takes place in the first instance, the stone serving as a nucleus, and that this adhesion is destroyed by the action of the sun's rays.

I have never seen any attempt to explain the phenomenon of bottom- frosts before this of J. M.'s, and I am not philosopher enough to speak positively on the subject; but the above is the way in which I have always endeavoured to account for it. Perhaps some of your scientific readers may be able to give much better reasons for it than have been offered either by J. M. or myself. (January 17th, 1832.)

Another writer (J. Carr, of Alnwick,) says that anchor frosts are merely long and severe ones where long masses of ice are frozen to the stones at the bottom of rapid streams, and this is simply owing to these stones acquiring a degree of cold far below the freezing-point, and the water in contact with them freezing and spreading into large sheets of ice, which are sometimes torn up and carry away the gravel adhering to the under surface.

Thinking that this was an error, I again wrote to the "Magazine of Natural History" as below:--

I perceive that others beside myself have endeavoured to account for anchor frosts. Mr. Carr says they never occur except in long and severe frosts, and that the adhesion of the ice to the stones at the bottom is owing to their acquiring a degree of cold far below the freezing-point. He is in error when he says they never occur except in long-continued frosts, as the walls of ice which are sometimes raised on the crowns of weirs are invariably (so far as my observations have extended) deposited there _before_ the water in the reservoir above is frozen over, which proves that the frost has not been of long continuance, although it may have been severe. As to what he says about the stones acquiring a degree of cold far below the freezing-point, and imparting that coldness to the water, I would just ask how it is that a stone at the bottom of a river acquires this excess of cold, and if it is not more probable that the stones impart warmth to the surrounding water? I can easily conceive how the stones may, by the action of the sun's rays upon them, warm the surrounding water; but I do not see how they can impart cold, or, in other words, how their temperature can be reduced below that of the water by which they are surrounded. Stones certainly impart warmth to the water they are in, in bright weather, as the rays of the sun do not give much warmth in passing through any transparent medium; but on coming in contact with any opaque bodies, the heat is absorbed or reflected as the case may be, and in this way transparent media such as air and water acquire a warmth by contact which they would not otherwise possess. Thus, if an anchor frost is followed by a bright day, the rays of the sun impart so much warmth to the stones at the bottom of the river as is sufficient to liberate the ice from them, and on such days thousands of pieces of ice may be seen rising from the bottom and floating down the streams.

Since my former observations were written I have had the satisfaction of finding my views on the subject confirmed by a very eminent chemist, [15] and if the discussions in your Magazine were to be settled by authority, and not by argument (which I trust will never be the case), he is one to whom many would be inclined to appeal, and to whom few would refuse to submit. (May 2nd, 1832.)

* * * * *

To the Editor of the "Agricultural Gazette."

In a leading article of the 10th of January, 1852, after an account of the effects produced on water by radiation and the protection afforded to plants by the ice with which ponds are covered in winter, you go on to say that there are some circumstances under which water-plants suffer greatly, and from a singular cause, but one which when looked into is sufficiently simple and intelligible. As you do not appear to have hit upon the true reason, allow me to quote a little further, and then give my reason for this singular effect.

You say that on a very fine but still night, water is cooled less rapidly than the earth: under such circumstances the bottom of the pond cools more rapidly than the surface, the plants become colder--in fact, some degrees below the freezing-point, &c. &c.

I submit that such reasons are inadmissible, for there would be an immediate upward current, which, as water is such an excellent conductor of heat, would immediately equalize the temperature of all the water above 40 degrees Fahrenheit, and stratified (if I may use the expression) above the water of this temperature there would be another layer of water of equal but gradually decreasing temperature until it fell below 32 degrees Fahrenheit.

The explanation I offer is this. It is well known that if water is kept perfectly still it may be cooled down considerably, or at least some degrees below 32 degrees, without freezing; but the moment it is shaken a portion of it is converted into a spongy, porous ice, and the temperature rises to 32 degrees.

What may be the case in the rivers of the South of England I do not know, but in the rapid streams of the North this process may be seen on a very extensive scale in severe frosts. The water in the still pools (before they are frozen over) is cooled down to below 32 degrees, and so soon as this cooled water reaches the next stream, precipitation (if I may so call it) takes place, and the spongy ice lays hold of every projecting pebble, which serves as a nucleus in the same way as threads and bits of stick serve in the crystallization of salts. After a severe frost, when followed by bright sunshine the next morning, I have seen thousands of these bits of spongy ice rising from the stones to which they had been attached to the surface of the water. I have seen after long- continued frost the course of a stream completely altered by this bottom-ice (as it is called here), and I have also seen a weir with a wall of ice on it three feet high (raised in a single night) by the same cause. Now apply this to the bottom-ice in ponds (which however I must confess I never saw). The night being calm, the water gets cool below 32 degrees, but then a breeze springing up the water becomes agitated, precipitation takes place, and the plants serving as nuclei become immediately clothed with this spongy ice, and the sun shining next morning imparts so much warmth to the plants that the ice thaws which is in contact with them, and rises to the surface. Of course if the sun does not shine next morning, and the frost continues, the plants may be clothed with ice for a long time.

To the foregoing the Editor of the "Agricultural Gazette" replied as follows:--

We cannot admit the soundness of our correspondent's explanation of the formation of bottom-ice or ground _gore_. We are well acquainted with the statements of Arago and other writers as to the cause of this curious phenomenon, and after a careful consideration of the subject believe that it is due to radiation and not to any other cause. Bottom-ice has been observed in ponds on perfectly still nights when there was no breeze to agitate the surface of the water.

The waters in the pools between the rapids of rivers can hardly ever be still enough for the water to fall below the freezing- point and yet remain fluid; the temperature of water in such situations is not below 33 degrees.

The following was my rejoinder:--

You say at the end of remarks about bottom-ice that you cannot admit the soundness of my explanation, and that you are well aware of what is said by Arago and others on this curious phenomenon, and that bottom-ice has been observed in ponds when there was no breeze, and that the water in pools between the rapids of weirs can hardly ever be still enough to fall below the freezing-point, and yet remain fluid.

I was not aware before seeing your remarks that either Arago or any other philosopher had ever written about bottom-ice, and even now I do not know what are their opinions on the subject, and if the discussions in your paper are to be settled by authority and not by argument, I can only make my bow and withdraw; but if it meets your views to allow your correspondents to state their opinions temperately, and support them by such arguments as occur to them, I do not yet feel inclined to give up my notions about bottom-ice. Will you allow me to ask whether you ever personally saw ice at the bottom of a pond when there was none on the surface? and if so, under what circumstances? I have heard of such an occurrence, but never witnessed it, and feel inclined to doubt the fact unless you will vouch for it; for it appears to me that the moment the water at the bottom falls below 40 degrees it will begin to rise to the surface, and it is so excellent a conductor that it will instantly equalize the temperature of the mud at the bottom with that of its own temperature.