Kitabı oku: «The Vast Abyss», sayfa 7
“Then we must lie in wait for whoever it is, when the fruit is ripe, and catch them.”
David shut both of his eyes tight, wrinkled his face up, and shook himself all over, then opened his eyes again, nodded, and whispered solemnly —
“Master Tom, we just will.”
Then he went off to the loading of the iron, saw the last load carted out, and was back ready, after shutting the gate, to take his master’s orders about turning the mill-yard into a shrubbery and garden.
A week with plenty of help from the labourers completely transformed the place. Then plenty of big shrubs and conifers were taken up from the garden, with what David called good balls to their roots, and planted here and there, loads of gravel were brought in, the roller was brought into action, and a wide broad walk led with a curve to the mill-door; there was a broad border round the tower itself, and a walk outside that; and Tom and Uncle Richard stood looking at the work one evening in a very satisfied frame of mind.
“There, Tom, now for tying up my money-bag. That’s all I mean to spend. Now you and I will have to do the rest.”
The next day was devoted to furnishing the interior with the odds and ends of scientific apparatus. The small telescope was mounted in the top-floor, the new apparatus, boxes, bottles, and jars were placed on tables and shelves in the middle floor, and the two great glass discs were carefully carried into the stone-floored basement, where a cask was stood up on end, a hole made in the head, and barrowful after barrowful of the fine silver sand plentiful in amongst the pine-trees was wheeled up and poured in, like so much water, with a big funnel, till the cask was full.
“What’s that for?” said Uncle Richard, in response to an inquiry from his nephew. “That, Tom, is for a work-bench, meant to be so solid that it will not move. Try if you can stir it.”
Tom gave it a thrust, and shook his head.
“I don’t think three men could push it over, uncle,” he said.
“Two couldn’t, Tom. There, that will do. We mustn’t have any accident with our speculum. Now then, to begin. Ready? Tuck up your sleeves.”
Tom obeyed, and helped his uncle to lift one of the glass discs on to the top of the cask, where it was easily fixed by screwing three little brick-shaped pieces of wood on to the head close against the sides of the glass.
Uncle Richard paused after tightening the last screw, and stood looking at his nephew.
“What a queer boy you are, Tom,” he said.
“Am I, uncle?” said the lad, colouring.
“To be sure you are. Most boys would be full of questions, and ask why that’s done.”
“Oh,” cried Tom, who smiled as he felt relieved, “I’m just the same, uncle – as full of questions as any boy.”
“But you don’t speak.”
“No, uncle; it’s because I don’t want you to think I’m a trouble, but I do want to know horribly all the same.”
“I’m glad of it, boy, because I don’t want what the Germans call a dummkopf to help me. I see; I must volunteer my information. To begin with then, that disc of glass is – ”
“For the speculum,” said Tom eagerly; “and you’re going to polish it.”
“Wrong. That’s only for the tool. The other is for the speculum, and we are going to grind it upon the tool.”
He turned to the other flat disc of ground-glass, where it lay upon a piece of folded blanket upon a bench under the window, and laid his head upon it.
“Doesn’t look much, does it, Tom?” he said.
“No, uncle.”
“And I’m afraid that all we have to go through may seem rather uninteresting to you.”
“Oh no, uncle; it will be very interesting to make a telescope.”
“I hope you will feel it so, boy, for you do not stand where I do, so you must set your young imagination to work. For my part, do you know what I can see in that dull flat piece of glass?”
Tom shook his head.
“Some of the greatest wonders of creation, boy. I can look forward and see it finished, and bringing to our eyes the sun with its majestic spots and ruddy corona, fierce with blazing heat so great that it is beyond our comprehension; the cold, pale, dead, silver moon, with its hundreds of old ring-plains and craters, scored and seamed, and looking to be only a few hundred miles away instead of two hundred and forty thousand; Jupiter with its four moons – perhaps we shall see the fifth – its belts and great red spot as it whirls round in space; brilliant Venus, with her changes like our moon; bright little Mercury; Saturn, with his disc-like ring, his belts and satellites; leaden-looking Neptune; ruddy Mars; the stars that look to us of a night bright points of light, opened out by that optic glass, and shown to be double, triple, and quadruple. Then too the different misty nebulas; the comets and the different-coloured stars – white, blue, and green. In short, endless wonders, my boy, such as excite, awe, and teach us how grand, how vast is the universe in which our tiny world goes spinning round. Come, boy, do you think you can feel interested in all this, or will you find it dry?”
“Dry, uncle! Oh!” panted Tom, with his eyes flashing with eagerness, “it sounds glorious.”
“It is glorious, my boy; and you who have read your Arabian Nights, and stories of magicians and their doings, will have to own that our piece of dull glass will grow into a power that shall transcend infinitely anything the imagination of any storyteller ever invented. Now, what do you say? for I must not preach any more.”
“Say, uncle!” cried Tom. “Let’s begin at once!”
“I beg pardon, sir,” said a pleasant voice; “but would you mind having a bell made to ring right in here?”
“No, Mrs Fidler,” said Uncle Richard; “we will lay down iron pipes underground to make a speaking-tube, so that you can call when you want me. What is it – lunch?”
“Lunch, sir!” said Mrs Fidler; “dear me, no; the dinner’s waiting and getting cold.”
“Bother the old dinner!” thought Tom.
“Come, my lad, we must eat,” said Uncle Richard, with a smile. “We shall not finish the telescope to-day.”
Chapter Twelve
“Now then, we’ll begin,” said Uncle Richard; “and the first thing is to make our mould or gauge, for everything we do must be so exact that we can set distortion at defiance. We must have no aberration, as opticians call it.”
“Begin to polish the glass, uncle?”
“Not yet. Fetch those two pieces of lath.” Tom fetched a couple of thin pieces of wood, each a little over twelve feet long. These were laid upon the bench and screwed together, so as to make one rod just over twenty-four feet long.
Then at one end a hole was made, into which a large brass-headed nail was thrust, while through the other end a sharp-pointed bradawl was bored, so as to leave its sharp point sticking out a quarter of an inch on the other side.
“So far so good,” said Uncle Richard. “Do you know what we are going to do, Tom?” Tom shook his head.
“Strike the curve on that piece of zinc that we are to make our speculum.”
“Curve?” said Tom; “why, it’s quite round now.”
“Yes; the edge is, but we are going to work at the face.”
“But arn’t you going to polish it into a looking-glass?”
“Yes; but not a flat one – a plane. That would be of no use to us, Tom; we must have a parabolic curve.”
“Oh,” said Tom, who only knew parabolas from a cursory acquaintance with them through an old Greek friend called Euclid.
“Be patient, and you’ll soon understand,” continued Uncle Richard, who proceeded to secure the sheet of zinc to a piece of board by means of four tacks at its corners, and ended by carrying it out, and fixing the board just at the bottom of the border, close to the window.
A couple of strong nails at the sides of the board were sufficient, and then he led the way in.
“Now, Tom, take that ball of twine and the hammer, and go up to the top window, open it, and look out.”
The boy did not stop to say “What for?” but ran up-stairs, opened the window, and looked out, to find his uncle beneath with the long rod.
“Lower down the end of the string,” he cried; and this was done, Tom watching, and seeing it tied to the end of the rod where the brass nail stuck through.
“Haul up, Tom.”
The twine was tightened, and the end of the rod drawn up till Tom could take it in his hand.
“Now take away the string.”
This was done.
“Get your hammer.”
“It’s here on the window-sill, uncle.”
“That’s right. Now look here: I want you to lean out, and drive that nail in between two of the bricks, so that this marking-point at my end may hang just a few inches above the bottom of my piece of zinc. I’ll guide it. That’s just right. Now drive in the nail.”
“Must come an inch higher, so that the nail may be opposite a joint.”
“Take it an inch higher, and drive it in.”
This was done, and the rod swung like an immensely long wooden pendulum.
“That’s right,” cried Uncle Richard; “the nail and this point are exactly twenty-four feet apart. Now keep your finger on the head of the nail to steady it while I mark the zinc.”
Tom obeyed, and looked down the while, to see his uncle move the rod to and fro, till he had scored in the sheet of zinc a curve as neatly and more truly than if it had been done with a pair of compasses.
“That’s all, Tom,” he said. “Take out the nail and lower the rod down again carefully, or it will break.”
All this was done, and Tom descended to find that both the rod and the sheet of zinc had been carried in, the latter laid on the bench, and displaying a curve deeply scratched upon it where the sharp-pointed bradawl had been drawn.
“There, Tom,” said Uncle Richard, “that curve is exactly the one we have to make in our speculum, so that we may have a telescope of twelve feet focus. Do you understand?”
“No,” said Tom bluntly.
“Never mind – you soon will. It means that when we have ground out the glass so that it is a hollow of that shape, all the light reflected will meet at a point just twelve feet distant from its surface. Now we have begun in real earnest.”
He now took a keen-edged chisel, and pressing the corner down proceeded to deepen the mark scored in the zinc with the greatest care, until he had cut right through, forming the metal into two moulds, one of which was to gauge the lower disc, the other the upper. The edges of these were then rubbed carefully together as they lay flat upon the bench, till their edges were quite smooth; then some of the unnecessary zinc was cut away, a couple of big holes punched in them, and they were hung upon a couple of nails over the bench ready for use.
“Next thing,” cried Uncle Richard, “is to begin upon the speculum itself, so now for our apparatus. Here we have it all: a bowl of fine sifted silver sand, a bucket of water, and a sponge. Very simple things for bringing the moon so near, eh?”
“But is that all we want, uncle?”
“At present, my boy,” said Uncle Richard, proceeding to wet some of the sand and pretty well cover the disc of glass fixed upon the cask-head. “That’s for grinding, as you see.”
“Yes, uncle; but what are you going to rub it with?”
“The other disc. Here, catch hold. Be careful.”
Tom obeyed, and the smooth piece of plate-glass was laid flat upon the first piece, crushing down the wet sand, and fitting well into its place.
“Now, my boy, if we rub those two together, what will be the effect?”
“Grind the glass,” said Tom. “I once made a transparent slate like that, by rubbing a piece of glass on a stone with some sand and water. But I thought you wanted to hollow out the glass?”
“So I do, Tom.”
“But that will only keep the pieces flat.”
“I beg your pardon, my boy. If we rub and grind them as I propose, one of the discs will be rounded and the other hollowed exactly as I wish.”
Tom stared, for this was to his way of thinking impossible.
“Are you sure you are right, uncle? Because if you are not, it would be so much trouble for nothing.”
“Let’s prove it,” said Uncle Richard, smiling. “Go to the kitchen door, and ask the cook for a couple of good-sized pieces of salt and the meat-saw.”
The cook stared, but furnished the required pieces, which were soon shaped into flat slabs with the saw. Then a sheet of newspaper was spread, and one of the flat pieces of salt placed upon the other.
“There you are, Tom,” said his uncle. “I want you to see for yourself; then you will work better. Now then, grind away, keeping the bottom piece firm, and the top going in circular strokes, the top passing half off the bottom every time.”
Tom began, and worked away, while from time to time the lower piece was turned round.
“Nice fine salt,” said Uncle Richard; “cook ought to be much obliged.”
“It will be as flat as flat,” said Tom to himself, “but I don’t like to tell him so.”
“There, that will do,” said Uncle Richard, at the end of ten minutes. “Now then, are the pieces both flat?”
“No, uncle; the bottom piece is rounded and the top hollowed, but I can’t see why.”
“Then I’ll tell you: because the centre gets rubbed more than the sides, Tom. There, take paper and salt back, and we’ll begin.”
Tom caught up the paper, and soon returned, eager to commence; and after a little instruction as to how he was to place his hands upon the top glass, Uncle Richard placed himself exactly opposite to his nephew, with the upturned cask between them.
“Now, Tom, it will be a very long and tedious task with this great speculum; hot work for us too, so we must do a bit now and a bit then, so as not to weary ourselves out. Ready?”
“Yes, uncle.”
“Then off.”
“It will be a tiresome job,” thought Tom, as, trying hard to get into regular swing with his uncle, the top glass was pushed to and fro from one to the other; but at each thrust Uncle Richard made a half step to his left, Tom, according to instructions, the same, so that the glass might be ground regularly all over. At the end of a quarter of an hour it was slid on one side, and more water and sand applied. Then on again, and the grinding continued, the weight of the glass making the task very difficult. But Tom worked manfully, encouraged by his uncle’s assurance that every day he would grow more accustomed to the work, and after two more stoppages there was a cessation.
“There!” cried Uncle Richard; “one hour’s enough for the first day. It wants faith to go on with such a business, Tom.”
As he spoke the future speculum was carefully lifted off the lower one, sponged with clean water, and on examination proved to be pretty well scratched in the middle in a round patch, but the marks grew less and less, till at the edge of the glass it was hardly scratched at all.
“There, you see where we bite hardest,” said Uncle Richard; “now we’ll give it a rest, and ourselves too.”
“But we shall never get done like this,” cried Tom.
“Oh yes, we shall, boy; and I’m not going to leave off our work. Let’s see: this we must call the workshop, the floor above our laboratory, and the top of course the observatory. Now then, let’s go up into our laboratory, and I’ll give you a lesson in elutriation.”
Chapter Thirteen
“I haven’t got a dictionary here, uncle,” said Tom, with a smile, as they stood at the massive table under the window in the laboratory. “I don’t know what elutriation means.”
“I dare say not. I didn’t till I was nearly fifty, Tom, but you soon shall know. Fetch that tin off the shelf.”
Tom obeyed, and found a label on the top, on which was printed “Best Ground Emery.”
“Well, you know what that is?”
“Emery? Powdered glass,” said Tom promptly.
“Wrong. Diamond cuts diamond, Tom, but we want something stronger than powdered glass to polish itself. Emery is a mineral similar in nature to sapphire and ruby, but they are bright crystals, and emery is found in dull blocks.”
“Then it’s very valuable?” said Tom.
“Oh, no. It is fairly plentiful in Nature, and much used. Now then, we want coarse emery to grind our speculum after we have done with the sand, and then different degrees to follow, till we get some exquisitely fine for polishing. How are we to divide the contents of that tin so as to graduate our grinding and polishing powder?”
“Sift it, of course, uncle.”
“And where would you get sieves sufficiently fine at last?”
“Muslin?”
“Oh, no. Here is where elutriation comes in, Tom; and here you see the use of some of the things I brought back from London the other day. To work. Bring forward that great pan.”
This was done.
“Now empty in the contents of this packet.”
Tom took up a little white paper of something soft, opened it, and poured the contents into the pan.
“Powdered gum arabic?” he said.
“Yes. Now empty the tin of emery upon it.”
Tom opened the tin, and found within a dark chocolate-looking powder, which felt very gritty between his finger and thumb. This he emptied upon the gum arabic, and, in obedience to instructions, thoroughly mixed both together.
“To make the fine emery remain longer in suspension,” said his uncle, “keep on stirring, Tom.”
“All right, uncle. What, are you going to pour water in? It’s like making a Christmas pudding.”
For Uncle Richard took up a can of water, and began to pour a little in as Tom stirred, changing the powder first into a paste, then into a thick mud, then into a thin brown batter, and at last, when a couple of gallons or so had been poured in and the whole well mixed, the great pan was full of a dirty liquid, upon the top of which a scum gathered as the movement ceased. This scum Uncle Richard proceeded to skim off till the surface was quite clear, and then he glanced at his watch.
“Is that scum the elutriation?” said Tom, with a faint grin.
“No, boy, the impurity; throw it down the sink. Now, Tom, we want to get our finest polishing emery out of that mixture, and it will take an hour to form – sixty-minute emery, the opticians call it; so while it is preparing, we’ll go and have another turn at the speculum.”
They descended, leaving the pan standing on the heavy table, and after spreading wet sand upon the lower disc of glass, the loose one was once more set in motion, and uncle and nephew, with quarter-hour rests for examination and wetting the surfaces, patiently ground away for an hour, by which time, upon the speculum being sponged, it was found that the greater part of the upper glass was deeply scratched.
“This is going to be an awfully long job,” thought Tom.
“Yes, it is,” said his uncle, who aptly read his thoughts, “a very long job, Tom; but good things have to be worked for, boy.”
“Oh, I’m not going to be tired, uncle. It’s like working for a grand prize.”
“It is. Now then, let’s see to the emery. Our finest must be ready by now. Now I want all the water, from which the emery has settled down to the bottom, drawn off into that great white basin. How is it to be done?”
“Pour it off,” said Tom.
“No; couldn’t be done without disturbing the bottom. Let’s try syphoning.”
Uncle Richard placed the basin upon a stool below the level of the table, took up a glass tube bent somewhat in the shape of a long-shanked hook, placed the short end gently beneath the surface of the nearly clear water, his lips to the long end, drew out the air, and the water followed directly from the atmospheric pressure, and ran swiftly into the basin.
As it ran, and Tom watched, Uncle Richard carefully held the short arm of the syphon, guiding it till the sediment at the bottom of the pan was nearly reached, when he quickly withdrew it, and the basin was then placed beside the pan.
“There, Tom,” said Uncle Richard, “that’s our sixty-minute emery.”
“But I thought you said you wanted it very fine. You’ve only washed it.”
“We’re playing at cross purposes, Tom,” said Uncle Richard. “You are talking about the contents of the pan, I about those of the basin.”
“What! the clear water – at least nearly clear?”
“Ah, there you have hit it, boy – nearly clear. That water contains our finest polishing powder, and it will have to stand till to-morrow to settle.”
“Oh!” said Tom, who felt very much in the dark, and he followed his uncle to the neat sink that had been fitted in the laboratory, and helped him wash a series of wide-mouthed stoppered bottles, which were afterwards carefully dried and labelled in a most methodical way.
“Saves time, Tom, to be careful,” said Uncle Richard, who now took up a pen and wrote upon the label of the smallest bottle “Emery, 60 min.”
“There, that’s for the contents of the big basin.”
“Want a genii to get a pailful into that little bottle, uncle,” said Tom, laughing.
“We’ll get all we want into it to-morrow, Tom,” was the reply. “Now then, how do you feel – ready for one hour’s more grinding at the speculum, or shall we leave it till to-morrow?”
“I want to finish it, and see the moon,” said Tom sturdily, as he rolled up his sleeves a little more tightly. “Let’s get on, uncle, and finish it.”
“Or get an hour nearer,” said Uncle Richard; and they went down and ground till Mrs Fidler summoned them to their meal.
