James Nasmyth: Engineer; an autobiography Part 26

It became bruited about that a ghost was seen at Patricroft!

A barge was silently gliding along the ca.n.a.l near midnight, when the boatman suddenly saw a figure in white.

"It moved among the trees with a coffin in its arms!"

The apparition was so sudden and strange that he immediately concluded that it was a ghost. The weird sight was reported at the stations along the ca.n.a.l, and also at Wolverhampton, which was the boatman's headquarters. He told the people at Patricroft on his return journey what he had seen, and great was the excitement produced. The place was haunted: there was no doubt about it! After all, the rumour was founded on fact, for the ghost was merely myself in my night-shirt, and the coffin was my telescope, which I was quietly shifting from one place to another in order to get a clearer sight of the heavens at midnight.

My ambition expanded. I now resolved to construct a reflecting telescope of considerably greater power than that which I possessed.

I made one of twenty inches diameter, and mounted it on a very simple plan, thus removing many of the inconveniences and even personal risks that attend the use of such instruments. (For ill.u.s.tration of the plan of mounting a large telescope, see p. 338) It had been necessary to mount steps or ladders to get at the eyepiece, especially when the objects to be observed were at a high elevation above the horizon.

I now prepared to do some special work with this instrument.

In 1842 I began my systematic researches upon the Moon. I carefully and minutely scrutinised the marvellous details of its surface, a pursuit which I continued for many years, and still continue with ardour until this day. My method was as follows: --

I availed myself of every favourable opportunity for carrying on the investigation. I made careful drawings with black and white chalk on large sheets of grey-tinted paper, of such selected portions of the Moon as embodied the most characteristic and instructive features of her wonderful surface. I was thus enabled to graphically represent the details with due fidelity as to form, as well as with regard to the striking effect of the original in its ma.s.ses of light and shade.

I thus educated my eye for the special object by systematic and careful observation, and at the same time practised my hand in no less careful delineation of all that was so distinctly presented to me by the telescope--at the side of which my sheet of paper was handily fixed.

I became in a manner familiar with the vast variety of those distinct manifestations of volcanic action, which at some inconceivably remote period had produced these wonderful features and details of the moon's surface. So far as could be observed, there was an entire absence of any agency of change, so that their formation must have remained absolutely intact since the original cosmical heat of the moon had pa.s.sed rapidly into s.p.a.ce. The surface, with all its wondrous details, presents the same aspect as it did probably millions of ages ago.

This consideration vastly enhances the deep interest with which we look upon the moon and its volcanic details. It is totally without an atmosphere, or of a vapour envelope, such as the earth possesses, and which must have contributed to the conservation of the cosmical heat of the latter orb. The moon is of relatively small ma.s.s, and is consequently inferior in heat-retaining power. It must thus have parted with its original stock of cosmical heat with such rapidity as to bring about the final termination of those surface changes which give it so peculiar an aspect. In the case of the earth the internal heat still continues in operation, though in a vastly reduced degree of activity. Again in the case of the moon, the total absence of water as well as atmosphere has removed from it all those denudative activities which, in the earth, have acted so powerfully in effecting changes of its surfaces as well as in the distribution of its materials.

Hence the appearance of the wonderful details of the moon's surface presents us with objects of inconceivably remote antiquity.

[Image] General structure of Lunar craters.

Another striking characteristic of the moon's surface is the enormous magnitude of its volcanic crater formations. In comparison with these, the greatest on the surface of the earth are reduced to insignificance.

Paradoxical as the statement may at first appear, the magnitude of the remains of the primitive volcanic energy in the moon is simply due to the smallness of its ma.s.s. Being only about one-eightieth part of the bulk of the earth, the force of gravity on the moon's surface is only about one-sixth. And as eruptive force is quite independent, as a force, of the law of gravitation, and as it acted with its full energy on matter, which in the moon is little heavier than cork, it was dispersed in divergent flight from the vent of the volcanoes, free from any atmospheric resistance, and thus secured an enormously wider dispersion of the ejected scoriae. Hence the building up of those enormous ring-formed craters which are seen in such vast numbers on the moon's surface--some of them being no less than a hundred miles in diameter, with which those of Etna and Vesuvius are the merest molehills in comparison.

I may mention, in pa.s.sing, that the frequency of a central cone within these ring-shaped lunar craters supplies us with one of the most distinct and unquestionable evidences of the true nature and mode of the formation of volcanoes.

They are the result of the expiring energy of the volcanic discharge, which, when near its termination, not having sufficient energy to eject the matter far from its vent, becomes deposited around it, and thus builds up the central cone as a sort of monument to commemorate its expiring efforts. In this way it recalls the exact features of our own terrestrial craters, though the latter are infinitely smaller in comparison. When we consider how volcanoes are formed-- by the ejection and exudation of material from beneath the solid crust-- it will be seen how the lunar eminences are formed; that is, by the forcible projection of fluid molten matter through cracks or vents, through which it makes its way to the surface.

[Image] Pico, an isolated Lunar Mountain 8000 feet high.

It was in reference to this very interesting subject that I made a drawing of the great isolated volcanic mountain Pico, about 8000 feet high.*

[footnote...

this ill.u.s.tration exhibits a cla.s.s of volcanic formations that may be seen on many portions of the moon's surface. They are what I would term exudative volcanic mountains, the results of a comparatively gentle discharge of volcanic matter, which has resulted in heaped up eminences; a vast group of which were displayed in the ill.u.s.tration, some of them being upwards of 20,000 feet high.

It exhibits a very different appearance from that of our mountain ranges, which are for the most part the result of a tangential action.

In the case of the earth, the hard stratified crust had to adapt itself to the shrunken diameter of the once much hotter globe. This tangential action is ill.u.s.trated in our own persons, when age causes the body to shrink in bulk, while the skin, which does not shrink to the same extent, has to accommodate itself to the shrunken interior, and so forms wrinkles--the wrinkles of age. This theory opens up a chapter in geology and physiology well worthy of consideration. It may alike be seen in the structure of the surface of the earth, in an old apple, and in an old hand.*

[footnote...

The shrunken hand on the other side is that of Mr. Nasmyth, photographed by himself. According to The Psychonomy of the Hand, by R. Beamish, F.R.S., author of The Life of Sir M. I. Brunel, it exhibits a thoroughly mechanical hand, as well as the hand of a delicate manipulator; ill.u.s.trating that remarkable expression in the Book of Job, that "in the hand of all the sons of men G.o.d places marks, that all the sons of men may know their own works."--ED.

[Image] Shrunken Apple and Hand.*

[footnote...

These ill.u.s.trations serve to ill.u.s.trate one of the most potent of geological agencies which has given the earth's surface its grandest characteristics. I mean the elevation of mountain ranges through the contraction of the globe as a whole. By the action of gravity the former larger surface crushes down, as it were, the contracting interior; and the superfluous matter, which belonged to a bigger globe, arranges itself by tangential displacement, and accommodates itself to the altered or decreased size of the globe. Hence our mountain ranges, which though apparently enormous when seen near at hand are merely the wrinkles on the face of the earth.

While earnestly studying the details of the moon's surface, it was a source of great additional interest to me to endeavour to realise in the mind's eye the possible landscape effect of its marvellous elevations and depressions. Here my artisic faculty came into operation. I endeavoured to ill.u.s.trate the landscape. scenery of the Moon, in like manner as we ill.u.s.trate the landscape scenery of the Earth. The telescope revealed to me distinctly the volcanic craters, the cracks, and the ranges of mountains--by means of the light and shade on the moon's surface. One of the most prominent conditions of the awful grandeur of lunar scenery is the brilliant light of the sun, far transcending that which we experience upon the earth--enhanced by the contrast with the jet-black background of the lunar heavens,-- the result of the total absence of atmosphere. One portion of the moon, on which the sun is shining, is brilliantly illuminated, while all in shade is dark.

While the disc of the sun appears a vast electric light of overpowering rayless brilliancy, every star and planet in the black vault of the lunar heavens is shining with steady brightness at all times; as, whether the Sun be present or absent during the long fourteen days'

length of the lunar day or night, no difference on the absolutely black aspect of the lunar heavens can appear. That aspect must be eternal there. No modification*

[footnote...

a small degree of illumination is, however, given to some portions of the Moon's surface by the Earth-shine, when the earth is in such a position with regard to the Moon, as to reflect some light on to it, as the Moon does to the earth.

of the darkness of shadows in the Moon can result from the illuminative effect, as in our case in the earth, from light reflected into shadows by the blue sky of our earthly day The intensity of the contrast between light and shade must thus lend another awful aspect to the scenery of the Moon, while deprived of all those charming effects which artists term "aerial perspective," by which relative distances are rendered cognisable with such tender and exquisite beauty. The absence of atmosphere on the Moon causes the most distant objects to appear as close as the nearest; while the comparatively rapid curvature of the moon, owing to its being a globe only one-fourth the diameter of the earth, must necessarily limit very considerably the range of view.

[Image] Lunar Mountains and Extinct Volcanic Craters

It is the combination of all these circ.u.mstances, which we know with absolute certainty must exist in the Moon, that gives to the contemplation of her marvellous surface, as revealed by the aid of powerful telescopes,--one of the grandest and most deeply interesting subjects that can occupy our thoughts; especially when we regard the physical const.i.tution and the peculiar structure of her surface, as that of our nearest planetary neighbour, and also as our serviceable attendant by night.

Then there are the Tides, so useful to man, preserving the sanitary condition of the river mouths and tide-swept sh.o.r.es.

We must be grateful for the Moon's existence on that account alone.

She is the grand scavenger and practical sanitary commissioner of the earth. Then consider the work she does! She moves hundreds of ships and barges, filled with valuable cargoes, up our tidal rivers, to the commercial cities on their banks. She thus performs a vast amount of daily and nightly mechanical drudgery. She is the most effective of all Tugs; and now that we understand the convertibility and conservation of force, we may be able to use her Tide-producing powers through the agency of electricity for mechanical purposes.

It is even possible that the Tides may yet light our streets and houses!*

[footnote...

It is not quite a century since London was in part supplied with water by the Moon, through employing the tidal action by the waters at Old London Bridge, where the tide mills worked the water-supplying pumps.

Is the moon inhabited? It seems to me that the entire absence of atmosphere and water forbids the supposition--at least of any form of life with which we are acquainted. Add to this adverse condition, the fact of the moon's day being equal to fourteen of our days; the sun shining with much more brilliancy of effect in the moon than on the earth, where atmosphere and moisture act as an important agent in modifying its scorching rays; whilst no such agency exists in the moon.

The sun shines there without intermission for fourteen days and nights.

During that time the heat must acc.u.mulate to almost the melting point of lead; while, on the other hand, the absence of the sun for an equal period must be followed by a period of intense cold, such as we have no experience of, even in the Arctic regions. The highest authorities state that the cold during the Moon's long night must reach as low as 250 degrees below the freezing point of water. These considerations, I think, reasonably suggest that the existence of any form of life in the Moon is in the highest degree improbable.

The first occasion on which I exhibited my series of drawings of the Moon, together with a map six feet in diameter of its entire visible surface, was at the meeting of the British a.s.sociation at Edinburgh in 1850. I always looked forward to these meetings with great pleasure, and attended them with supreme interest. My dear wife always accompanied me. It was our scientific holiday. It was also our holiday of friendship. We met many of our old friends, and made many new friends. Alas, how many of them have departed! Herschel, Faraday, Robinson, Taylor, Phillips, Brewster, Rosse, Fairbairn, La.s.sell, and a host of minor stars, who, although perhaps wanting in the brightness or magnitude of those I have named, made good amends by the warmth of their cheerful rays. We saw the younger lights emerging above the horizon: the men who still continue to shed their glory over the meetings of the a.s.sociation.

How delightful was our visit to Edinburgh in 1850. It was "mine own romantic town." I remembered its striking features so well.

There was the broad ma.s.s of the Old Town, with its endless diversity of light and shade. There was the grand old fortress, with its towers and turrets and black portholes. Towards evening the distant glories of the departing sun threw forward, in dark outline, the wooded hill of Corstorphine. The rock and Castle a.s.sumed a new aspect every time I looked at them. The long-drawn gardens filling the valley between the Old Town and the New, and the thickly-wooded scars of the Castle rock, were a charm of landscape and a charm of art. Arthur's Seat, like a lion at rest, seemed perfect witchcraft. And from the streets in the New Town, or from Calton Hill, what singular glances of beauty were observed in the distance--the gleaming waters of the Firth, and the blue shadows among the hills of Fife.

I remembered it all, from the days in which I sat, as a child, beside the la.s.sies watching the "claes" on the Calton Hill and hearing the chimes of St. Giles's tinkling across the Nor' Loch from the Old Town; the walks, when a boy, in the picturesque country round Edinburgh, with my father and his scientific and artistic friends; my days at the High School, and then my evenings at the School of Arts; my castings of bra.s.s in my bedroom, and the technical training I enjoyed in the workshop of my old schoolfellow; my roadway locomotive and its success; and finally, the making of my tools and machines intended for Manchester, at the foundry of my dear old friend Dougla.s.s. It all came back to me like a dream. And now, after some twenty years, I had returned to Edinburgh on a visit to the British a.s.sociation. Many things had been changed--many relatives and friends had departed--but still Edinburgh remained to me as fascinating as ever.

The excursions formed our princ.i.p.al source of enjoyment during these scientific gatherings. The season was then at its happiest.

Nature was in her most enjoyable condition, and the excursionists were usually in their holiday mood. The meeting of the British a.s.sociation at Edinburgh was presided over by Sir David Brewster. The geologists visited the remarkable displays of volcanic phenomena with which the neighbourhood of Edinburgh singularly abounds. Indeed, Edinburgh owes much of its picturesque beauty to volcanoes and earthquake upheavings.

Our excursions culminated in a visit to the Ba.s.s Rock. The excursion had been carefully planned, and was successfully carried out.

The day was beautiful, and the party was of the choicest.

After reaching the little cove of Canty Bay, overlooked by the gigantic ruins of Tantallon Castle, we were ferried across to the Ba.s.s; through a few miles of that capricious sea, the Firth of Forth, near to where it joins the German Ocean. We were piloted by that fine old British tar, Admiral Malcolm, while the commissariat was superintended by General Pasley.

We were safely landed on that magnificent sea-girt volcanic rock-- the Ba.s.s. After inspecting the ruins of what was once a castellated State prison, where the Covenanters were immured for conscience' sake, we wandered up the hill towards the summit. There we were treated to a short lecture by Professor Owen on the Solan Goose, which was ill.u.s.trated by the clouds of geese flying over us.

They freely exhibited their habits on land as well as in mid-air, and skimmed the dizzy crags with graceful and apparently effortless motions. The vast variety of seafowl screamed their utmost, and gave a wonderfully ill.u.s.trative chorus to the lecture.

It was a most impressive scene. We were high above the deep blue sea of the German Ocean, the waves of which leapt up as if they would sweep us away into the depths below.

Another of our delightful excursions was made under the guidance of my old and dear friend Robert Chambers.*

[footnote...

I cannot pa.s.s over the mention of Robert Chambers's name without adding that I was on terms of the most friendly intimacy with him from a very early period of his life to its termination in 1871.

I remember when he made his first venture in business in Leith Walk.

By virtue of his industry, ability, and energy, he became a prosperous man. I had the happiness of enjoying his delightful and instructive society on many occasions. We had rare cracks on all subjects, but especially respecting old places and old characters whom we had known at Edinburgh. His natural apt.i.tude to catch up the salient and most humorous points of character, with the quaint manner in which he could describe them, gave a vast charm to his company and conversation.

Added to which, the wide range and accuracy of his information, acquired by his own industry and quick-witted penetration, caused the hours spent in his society to remain among the brightest points in my memory.

The object of this excursion was to visit the remarkable series of grooved and scratched rocks which had been discovered*

[footnote...

They had been first seen, some twenty years before, by Sir James Hall, one of the geologic lights of Edinburgh.

on the western edge of the cliff-like boundary of Corstorphine Hill.

The glacial origin of these groovings on the rocks was then occupying the attention of geologists. It was a subject that Robert Chambers had carefully studied, in the Lowlands, in the Highlands, in Rhine-land, in Switzerland, and in Norway. He had also published his Ancient Sea Margins and his Tracings of the North of Europe in ill.u.s.tration of his views. He was now enabled to show us these groovings and scratchings on the rocks near Edinburgh. In order to render the records more accessible, he had the heather and mossy turf carefully removed-- especially from some of the most distinct evidences of glacial rock-grooving. Thus no time was lost, and we immediately saw the unquestionable markings. Such visits as these are a thousand times more instructive and interesting than long papers read at scientific meetings. They afford the best opportunity for interchange of ideas, and directly produce an emphatic result; for one cannot cavil about what he has seen with his eyes and felt with his hands.