Part 10

“It is probable,” he replied, “that there is some general temperature that suits them best, or that is most productive of those insects on which they prey; and as the seasons change, that temperature can only be obtained by approaching the equator, or perhaps by passing into a corresponding latitude of the southern hemisphere. A circumstance mentioned by our friend Colonel Travers, made a strong impression on me:--when he was going up the Mediterranean, I think in the latter end of April, a great number of swallows settled on the yards and rigging of the ship; they began to alight there about sun-set, and before nine o’clock some thousands had collected; but in such an exhausted state that they immediately went to sleep, and allowed themselves to be handled without making any attempt to escape. At daylight next morning they rose, as if by a single impulse, and flew away to the northward; and several prodigious flights of the same bird were observed, at a great height in the air, pursuing the same course towards Europe.

“Poor creatures,” said Frederick, “they must have come all the way from the north coast of Africa. Can you tell me, father, in what part of the Mediterranean this happened, that I may measure on the map the distance they had flown?”

“I do not recollect,” said my uncle; “but if I am right in my ideas of their swiftness, the widest part of that sea would be the affair of a few hours. It has been estimated that a swallow usually flies a mile in a minute; and sixteen or seventeen hours daylight will give about a thousand miles for a single day’s journey at that velocity. Now when you recollect that here we see those birds continue on the wing the whole day without the least appearance of being tired, we can only account for the extraordinary fatigue of those which perched on the Colonel’s ship, by supposing their flight to have continued for several days; and thus three or four days’ exertion might have brought them from a country bordering on the southern tropic.”

I reminded my uncle of the account we had lately read in Dr. Brewster’s Journal of Science, about the rapid flight of the wild pigeons that cross America in search of food.

“Yes,” said he, “and there is a curious fact recorded in that paper, which satisfactorily demonstrates, that the sustained velocity with which some birds remove from one district to another, in search of food, is not confined to the instinctive energy which belongs to the time of annual migration, but that it is their habitual and daily practice. The circumstance to which I allude is this: pigeons have been killed in New York, whose craws were still filled with fresh rice, which must have been collected in Carolina; and, therefore, as the pigeon digests its food very quickly, they could have been but a few hours performing a journey of three hundred miles. But we need not go so far off for examples of the ease and rapidity with which pigeons go to great distances in quest of some favourite food; for it is well known that in the vetch season in Norfolk, the Dutch pigeons come over in the morning, and return to Holland in the evening.”

Mary shewed us a passage in the voyage of La Pérouse, which proves that swallows do go a long way to the southward. “A swallow of the common species, undoubtedly lately come from Europe, followed us for some time without alighting on the vessel, but soon directed its flight towards the African coast, where it was sure of finding the insects on which it feeds. We were in 28° N. lat., and 22° W. long.” Adanson also asserts that he witnessed the arrival on the coast of Senegal, on the 6th of October, in the evening, of real European swallows; and he ascertained that they are never seen there but in autumn and winter.

My aunt has often observed them collected in large companies on trees, and on the roofs of houses, previous to their flight in September; and the direction they take at that season is to the southward.

My uncle then told us, that his old and highly respected friend Dr. Jenner, who, you know, lived just on the other side of the Severn, used to remark, that if swallows really did creep into holes and crevices to hibernate, they would surely appear in a languid state when they came out again--in the same way that all those quadrupeds who pass the winter in a state of torpor, are very much emaciated when they revive. The hedgehog, for instance, at the approach of winter, retires to its nest covered with fat, which is entirely absorbed when it awakens on the return of spring; whereas when the swallows appear in April, they are plump and strong upon the wing.

Mary added, that swallows have two broods during the summer, and that she had somewhere read, that it was only the strong early brood that took flight to warmer regions; but that the young birds hatched late in the year, being incapable of distant migration, seek shelter in holes and hollow trees, and wherever they can lurk in safety in the winter.

Mary afterwards shewed me a passage about swallows in Latrobe’s Journal, a book which I have more than once mentioned to you. He writes from the settlement of Groenkloof, to the north of Cape Town.

“Every morning I am greeted by the pleasant chirping of two swallows which have a nest in the corner of my room, under the ceiling. There is hardly a room, kitchen, or outhouse, in the country, without these inmates, and it would be thought next to murder to kill them. They build their nests of clay in the shape of a bottle; they line them with the softest down, and, though they leave the country during the winter, the same birds always return to the same nests after their emigration. As the room doors usually stand open in the day, they go in and out whenever they please; but if the door is shut, they give notice of their wish to go abroad, by a gentle piping and flying about the room; and no one thinks it troublesome to let them out: indeed, I have often left my bed to open the door for them.”

I forgot to mention that my uncle told us there was no country in the world which was not visited by these little swift-winged creatures. They were seen, for a short time, even in the frozen regions of Baffin’s Bay and Melville Island; and Captain Franklin says, they made their first appearance at Great Bear Lake the middle of May, to feast on the mosquitoes and other insects that abound on the northern shores of America. Wentworth says, they may be literally called cosmopolites.

_31st._--After dinner yesterday, the conversation turned on the importance of the palm tribe in their native countries to the inhabitants. Sago, cocoa-nuts, dates, oil, and various other articles of excellent food which they produce, were all discussed; and each of us mentioned some of the many uses to which the stems, the leaves, and the fibrous parts were applied. Miss Perceval afterwards endeavoured to explain the botanic distinctions between palms and tree-ferns, which have so many points of resemblance in their mode of growth: but my aunt suggested, that her description would be much more interesting if we were looking at the plants; and she kindly proposed another expedition to those magnificent stoves of Lord S. that we had seen with so much pleasure last autumn.

Miss P. approved of this arrangement, and she has been exceedingly gratified to-day with all she saw; but none seemed to be more delighted with our visit than the old gardener. He perceived how well she could appreciate his difficulties and his success; and he listened with the greatest attention to all her remarks. Miss P., however, did not forget the circumstance that led to our visit, and she shewed us in several different palms, that the scales of the foot-stalks completely sheath the stem; and that after the decay of the leaf they form an entire ring, which has a very different appearance from the separate marks or cicatrices left by the fronds of the fern.

She had never seen so fine a collection of palms in this country; and she told us many circumstances of their history and habits. She made us observe, that in the leaves the fibres run parallel to the edges. There are two grand forms to which the leaves may all be referred; pinnated, as in the cocoa and date; and fan-shaped, as in the dwarf and fan-palms. In the dwarf which we examined, the breadth of the leaf is considerable, but from the direction of the fibres, and the manner in which it is folded, previous to developement, it may rather be regarded as composed of several leaves.

The flowers of palms are even more numerous than I thought, though I remember, at Rio, trying in vain to count those of the _alfonsia amygdalina_--it would have been a hopeless work, for Miss P. says one spathe sometimes contains sixty thousand.

Some palms are gregarious, forming large woods, and naturally spreading over whole districts; as the dwarf palm does in the South of Europe. She says, that the different species are never much intermixed; though their districts are small, they are generally distinct from each other. It is remarkable, that no palm of the old world is found in America, except the cocoa-nut and the oil-palm of the coast of Guinea; and that there is but one species common to Asia and Africa. The palms of New Holland, also, are peculiar to that country; and I believe that she said, those of the Mauritius only occur in those islands. The cocoa, the date, and the sago palms, are the most widely distributed; but the true home of the palms is the torrid zone; for, of 110 well known species, only twelve are found outside the tropics.

I asked Miss P. whether the leaves which are found lining the tea-chests, belong to a palm. Certainly not, she said, nor to any of the cane families, as is evident from the want of a mid-rib; it is generally believed that they belong to some of the grass tribes, and indeed very closely resemble the broad-leaved _pharus_.

My uncle pointed out to her several large and flourishing plants of the _ficus elastica_, or caoutchouc tree. They have succeeded so well for the last two years in a stove kept at a very low temperature, that some of them are now removed to the green-house, and even one or two are put out of doors. As we drove home, I asked my uncle at what time caoutchouc, or Indian rubber, was brought to this country.

“It appears,” said he, “to have been first introduced into Europe, about the middle of the last century; and is, I am sure you know, procured from two other South American plants, as well as from the ficus; I mean the _hævea_ and the _jatropha_. The juice, which is obtained by an incision in the bark, is made to spread itself in successive layers, over clay moulded into the form of a bottle, and when sufficiently thick, it is hung over the smoke of burning wood, which hardens, and gives it a dark colour: the clay is afterwards crumbled and thrown out. It is fabricated, by the inhabitants of its native country, into vessels to contain water and other liquids; and it is in some places used by the fishermen for torches.

“Caoutchouc is also procured from a climbing plant, _urceola_, a native of Sumatra. If one of its thick old stems be cut, a white juice, like cream, oozes out; by exposure to the air, a decomposition takes place, and while part of it concretes, a thin whitish juice is separated. Cloth well covered with this juice, becomes impervious to water; and the pieces so prepared are easily joined together by applying fresh juice to the edges.”

I asked my uncle, on our road home, if it was by means of that juice that the water-proof cloth, which he had seen in London, was prepared.

He answered, that he had seen some of the juice at the Royal Institution, where it had been brought from Mexico to be analysed; but that, in general, caoutchouc was imported in a solid state. “A cheap method,” he continued, “of dissolving it was discovered by Mr. Mackintosh; and his mode of applying it to cloth, linen, silk, or any materials of that kind, was equally ingenious and useful. When reduced to a fluid state, a sufficient coat of it is laid upon the cloth, and another piece being then spread over it and pressed together, they become permanently united as well as water-proof; but as the outside and the inside need not be similar, you may have the one of cloth, and the other of velvet; or a camlet cloak lined with silk, or any other combination you please.

“There are many other purposes to which this contrivance has been applied. _Hoses_ for conveying the water from fire-engines, when made of canvas and caoutchouc, and without seam, are much stronger, more durable, and more flexible than those made of leather. I have been told by a naval officer that a hose of this sort affords an excellent mode of filling the casks in a boat, from a well or stream near the shore, when a heavy surf prevents their being landed; for it is obvious that such a hose may pass through the sea, without the possibility of the fresh water it conducts being tainted by the salt. It is also well adapted to tilts for waggons and hayricks; it would make admirable military tents; and you may imagine what a comfort water-proof bags must have been in Captain Franklin’s expedition to the Polar Sea, in keeping the men’s clothes dry, notwithstanding the dismal weather to which they were so often exposed.

“There is only one more use which I will now mention. Any substance that is carefully coated with this gum is as impervious to air as to water: bags therefore made in the shape of cushions or pillows, which can be folded up and carried in the pocket, may be in a few moments inflated with the breath, by means of a small pipe; and even beds, which when empty would occupy but little room in a portmanteau, would often preserve the health, and greatly add to the comfort of travellers in certain countries, where a dry, clean, and soft bed is an unattainable luxury.”

Miss Perceval told us that in some of the forests of Guiana, a substance, called _dapicho_ by the Indians, is found in large masses under ground; and which, having all the properties of the recent gum, was long known by the name of fossil caoutchouc. But the indefatigable Humboldt, having at last succeeded in finding some of it undisturbed in the ground, at once perceived that it had oozed out of the roots of caoutchouc trees which were so old that the interior had begun to decay. It is white and brittle, till exposed to a strong heat; and when sufficiently beaten with a heavy club it acquires great elasticity. The Indians make their famous tennis balls of it; it is also cut into corks, which are very superior to those made of the cork tree; and it is worked up into enormous drum-sticks--the drum being merely a hollow cylinder of wood about two feet long.

“There is, however,” my uncle observed, “a species of fossil caoutchouc. It is, in fact, a bitumen, but flexible and elastic; and, as it has the property of cleaning off pencil-marks in the same manner as Indian rubber, it has been named mineral caoutchouc.”

I asked him if it might not be some of the dapicho, which had lain buried in the ground, long since the trees, from which it oozed, had perished?

“I have but two reasons, Bertha, to oppose to your theory. It is only found near Castletown in Derbyshire, and you know the English climate is not very well suited to those trees--and secondly, it is in the deep recesses of a lead mine, surrounded by spar and limestone.”

_June 1st._--You may remember, mamma, how much I was interested, last year, by my uncle’s illustrations of the Mirage and the Fata Morgana. The subject was often afterwards alluded to in conversation; and my aunt having incidentally mentioned it to her charming correspondent in Upper Canada, I was this afternoon agreeably surprised by her reading aloud the following passage in a letter which she had just opened:--

“Your young friend Bertha will be pleased to hear that last June I witnessed something very like that curious phenomenon which you say interested her so much. One morning I awoke just at the break of day, and accidentally directing my eyes to the window, which has a southern aspect, I was astonished to see--instead of the black monotonous forest by which we are surrounded--a wide, magnificent sheet of water, connected with a spacious river winding to a great distance, and confined by gentle slopes and grassy banks; and all this so distinct that the bright fresh green of the young leaves was beautifully contrasted with the dark foliage of the pine woods.

“I rubbed my eyes, and looked again--for it appeared to be exactly our lake near Peterborough, with the Otanabee River winding towards Rice Lake, except that the whole view was reversed. I wondered how all this could be seen over our lofty trees, and I went to the window and leaned out to look for objects which I knew--but nothing was to be seen except my beautiful and inexplicable landscape. I lay down--and still saw it from my pillow;--but my eyes gradually closed--and, when I again wakened, heavy mists had risen with the sun--and my fairy prospect had vanished.

“I now recollected the description I had long ago read of the Fata Morgana, and I was satisfied that this was no vision of my fancy, but the reflection of real scenery upon some peculiar vapour which only appears at that early hour of the morning.”

_2nd._--I spent a great part of this morning in examining the ingenious leaf-nests of some little caterpillars, which Mary says are the larvæ of the _tinea_ moths. She explained to me their construction. The caterpillar fixes a number of fine silken cords from one edge to the other of the leaf, and by pulling at them with its many strong feet, the sides are gradually forced to approach each other till they meet, when it fastens them together with short threads. Sometimes the large nerves of the leaf are too strong to yield to these efforts, and the clever little creature immediately weakens them by gnawing them half through, in different places. I could distinctly perceive those places in several of the leaves which we opened. Some species cut out a long triangular portion from the edge of the leaf, and form it into a conical roll, like a paper of comfits: in one spot, however, they let it remain attached to the leaf, by way of a base; and then, by fastening little cords to the point of the cone, it is actually pulled upright on the remainder of the leaf, where it stands like a tent. But there are other tineæ which shew still more dexterity in constructing their habitations. Some of them we found on the under sides of the leaves of the rose-tree, apple, elm, and oak; and Mary made me observe how nicely they form an oblong cavity in the interior of the leaf, by eating the pulpy substance between the two membranes composing its upper and under sides. The detached pieces are then joined with silk, so as to make a case or horn, which is cylindrical in the middle, with an orifice at each end, the one being circular and the other triangular; and the seam is so artfully made, as to be scarcely perceptible even with a glass. Were this case all circular, it would be more simple, but the different shape of the two ends renders it necessary that each side should be cut into a different curve.

But I should fill my whole journal, were I to tell you all the beautiful contrivances of these insects, and the instinct, or, I might say, the reason which appears in all their contrivances.

_3rd._--My uncle mentioned yesterday, that in returning a few years ago from Berwick upon Tweed, he was much surprised, as night came on, at seeing two immense fires near Newcastle. Upon inquiring, he found that they were the small coal which does not readily sell, and is therefore separated by screens from the larger blocks. Prodigious heaps are thus formed at the mouths of the pits; and from the decomposition of the pyrites, they take fire, and continue to burn for years. One of these huge mounds was but a few miles from the road; it was said to cover twelve acres of ground, and to have been burning for eight years.

As all that small coal might be made use of to produce coal gas, he says the legislature should interfere to prevent such a shameful waste, for not less than one hundred thousand chaldrons are thus annually destroyed on the banks of the River Tyne; and nearly the same quantity on the Wear. Beneath these burning heaps, he found a bed of blackish scoria, which resembles basalt, and which is used for mending the roads.

To the west of Dudley, in the great Staffordshire coal district, my uncle says that some of the collieries took fire spontaneously many years ago. The subterraneous conflagration spread to a great extent, and produced some singular effects; smoke and steam were seen to rise from the earth, the vegetation appeared to be hastened by the heat, and even the ponds were warm. What was still more remarkable, where the ignited part of the coal came near the surface, the argillaceous strata (or potter’s-clay) covering it have been converted, by the intense heat, into a species of porcelain jasper, which is sometimes beautifully striped; this last circumstance being caused by the various degrees of oxidation of the iron that is contained in the clay.

_4th, Sunday._--This morning--perhaps the last Sunday that we shall spend at Fernhurst for many months--my uncle finished explaining to us the three dispensations; and it made the more impression on me, as I fear that, on our journey, we shall not have any of those regular Sunday conversations, which have been so instructing and satisfactory.

“The object of the Christian Dispensation,” said he, “was to ratify the promises of redemption and of eternal life, through the merits of a divine mediator. What the former dispensations announced as _to come_, this concluding dispensation has exhibited in actual accomplishment. The long-expected Redeemer has been manifested; he has made the promised atonement for the sins of mankind; he has shewn himself as the mediator of the new covenant, and the doubts of ages have vanished before the light of the Gospel.”

I ventured to interrupt my uncle, to ask why it is called the _new_ covenant, as if it was of a different nature from the two former ones.

“It is so styled,” he answered, “not as being new in its nature, or different from those which preceded it; but merely as being new, or last, in order, and therefore superseding all others. The typical sacrifices of the two former were, you know, the symbols of the real victim who consummated the Christian covenant. In each of them provision was made for the reconciliation of fallen man; and the object of each being the same, the terms were the same: Jehovah graciously promising on his part to accept the meritorious death of the Messiah, as a full acquittal and satisfaction of all sin; but, on the two-fold condition, of faith, and of obedience on our part.

“The doctrine of atonement through the sufferings of the Mediator, forms the basis of each of the covenants, and is justly considered by all those who take their religion from Scripture as the corner-stone of the Christian dispensation. The proofs of this essential tenet are as numerous as they are clear and explicit; and in the last discourse which our Saviour held with his disciples, and which is fully recorded by St. John, you will find it very distinctly stated.