Chapter 8

On the permanency of such forces and their mutual play the universe rests, and its wonderful history. With the collapse of any of them it would cease to have any more a footing in space, and all its elements would rush into instant confusion. What a Hand, therefore, that must be which holds them up, and what a Wisdom which guides their movements! Verily, He that sends them forth and bids them work His will is greater than any one--greater than all of them together. How insignificant, then, should we seem before Him who rules them on the wide scale by commanding them, while we can only rule them on the small by obeying them! And yet how benignant must we regard Him to be who both wields them Himself for our benefit and subjects them to our intelligence and control!

FOOTNOTES:

[B] This paper on "Attraction" is the substance of a lecture which I composed on the basis of notes taken by me when. I had the honour of attending the Prince of Wales at the course given, on the same subject by the late Professor Faraday. The Professor, having seen the _resumé_ I had written, warmly commended the execution, and generously accorded me his sanction to make any use of it, whether for the purpose of a lecture or otherwise, as might seem good to me. It is on the ground of this sanction I feel warranted to print it here.

_THE OIL FROM LINSEED_.

Various processes have for a long time been in use for the purpose of extracting the oils from different species of nuts and seeds, a few of the more interesting of which are not unworthy of brief notice and description.

In Ceylon, where cocoa-nuts and oil-producing seeds abound, the means employed by the natives in the last century for extracting the oils were of a most primitive character. A few poles were fixed upright in the ground, two horizontal bars attached to them, between which a bag containing the pulp of the seed or nut was placed. A lever was then applied to the horizontal bars, which brought them together, thus creating a pressure which, by squeezing the bag, gradually expressed the oil from the pulpy substance. This rude machine was at that time of day one of the most approved for the purpose.

The system of pestle and mortar was also in use, but as the process was necessarily very slow, this method was seldom resorted to. An improvement on this system was invented by a Mr. Herbert, whose design it had been to construct a powerful and efficient machine which should combine cheapness and simplicity. It consisted of three pieces of wood, viz., an upright piece fixed in the ground, from the lower and upper extremities of which there projected the two other pieces, the top one attached to the joint of a long horizontal lever, and the lower one to the joint of a vertical one. The fixed upright post and the horizontal lever formed the press. The bag of pulp being put between the upright one and the vertical, the pressure was obtained by suspending a negro or a weight from the lever.

In another press of the same or a similar kind, the bags were placed in a horizontal frame, and a loose beam of wood pressed down on it by a lever.

Another form of press had cambs and wedges; also a modification of it by Mr. Hall of Dartford, who applied the pressure by means of a steam-cylinder. The cambs are arranged alternately, so that one is filled while the other is being pressed. This brief notice will suffice to give an idea of such machines as are wrought by lever pressure.

We pass on, therefore, to later inventions and improvements.

First, The Dutch or _stamper_ press, invented in Holland; second, the _screw_; and, third, the _hydraulic_:--

(1.) _The stamper press_ is something like a beetling-machine, in which wedges are driven in between the bags, containing, of course in a bruised condition, the seed to be pressed.

(2.) _The screw press_ has an ordinary square-threaded screw, and it acts in the same way as press for making cider or cheese.

(3.) _The hydraulic press_. Here the pressure is produced by means of a piston driven up by the force of water, the immense power of which is, in great part, due to its almost total incompressibility. This is by far the most perfect form of press. Its power must be familiar to all who remember the lifting of the tubes of the Britannia Bridge, and the _launching of the Great Eastern_.

An oil-mill is in form something like a flour-mill. The operation begins at the top, where the seed is passed through a flat screw or shaker and then through a pair of rollers, which crush it. These rollers are of unequal diameter, the one being 4 feet, and the other 1 foot; but they are both of the same length, 1 foot 4 inches, and make fifty-six revolutions in a minute. By this arrangement it is found the seed is both better bruised and faster than when, as was formerly the case, the rollers were of the same diameter. A pair of rollers will crush 4-1/2 tons of seed in eleven hours, a quantity enough to keep two sets of hydraulic presses going.

After the seed is crushed in this way, it is passed under a pair of edge stones. These stones weigh about seven tons, are 7 feet 6 inches in diameter and 17 inches broad, and make seventeen revolutions a minute. If of good quality, they will not require to be faced more than once in three years, and they will last from fifteen to twenty. They are fitted with two scrapers, one for raking the seed between the stones, the other for raking it off at the proper period. One pair of stones will grind seed sufficient for two double hydraulic presses, and the operation occupies about twenty-five minutes. The seed is now crushed and ground, but before it is passed on to the press it is transferred to the heating-kettle.

The heating-kettle is composed of two cylindrical castings, one fitting loosely into the other, so that a space is left between them for a free circulation of steam all round both the sides and bottom of the interior vessel. The internal casting is again divided horizontally into two partitions, one above the other therefore, by two plates, between which also there is a space left for the admission and circulation of steam; and a communication is kept up between the upper compartment and the under by means of a stripping valve. Besides this, there is a communication from the internal kettle through the external one, and also a shaft passes between the two horizontal parts to give motion to the stirrer, which revolves thirty-six times a minute. A cover encloses the top, and it is through this the vessel is charged. The upper portion is filled first, where the contents introduced are allowed to remain ten or fifteen minutes, after which the valve is opened and the whole falls into the lower kettle, where it is kept till wanted. The seed is then taken away from the lower kettle by an opening, and bestowed in bags of sufficient size to make a cake of 8 lbs. weight after the oil is pressed out of it. Indeed, the compartments of the heating-kettle are of a size to contain enough to charge one side of a hydraulic press. These, therefore, are so constructed as to render the operation continuous, the upper one being discharged into the under as soon as its contents are withdrawn to the press. The seed is heated to the temperature of 170 degrees Fahr., when it is drawn off and placed in the bags.

In another form of kettle the seed is heated on a hot hearth, and on the top of the hearth is a loose ring, within which a spindle revolves to stir the seed. After the requisite temperature has been reached, the ring is raised and the seed swept into the bags, which are made of horse-hair. There is great loss of heat in this method, however, as the seed is exposed to the atmosphere, which of course cools it.

We now come to the final operation, the mode of expressing the oil. The screw press we do not need to describe, as it consists simply of two plates, brought together by a screw, in the same way as the press used for squeezing apples in the manufacture of cider, and the cheese press. Let us look therefore at the stamper press. It consists of an iron box, open at the top, at each end of which are two plates, capable of containing between them a bag of seed which shall yield a cake weighing 9 lbs. To one of the inner plates of the box is attached a wedge, beside which is inserted another filling up, and then the driving wedge is introduced; and lastly, another block is let in between this wedge and the other plate as soon as the bags have been placed vertically in the press-box. A stamper of wood, worked by cambs on a revolving shaft, is allowed to fall about 1 foot 10 inches, at the rate of fifteen strokes a minute, for about six minutes. This stamper is 16 feet long by 8 inches square, and falls on the head of the wedge, and drives it in to a level at the top of the box. Another stamper is employed to drive down an inverted wedge, so as to release the working one, and enable the attendant to take out the cake. A press of this kind will turn out only about 12 cwts. of cake a day.

We come now to the hydraulic press. This is certainly the most approved invention that has yet been adopted, and it is simply a Bramah press adjusted for the purpose. It has been in use for about thirty years, though it was, of course, at first less skilfully and scientifically constructed than it is now. In one of the earliest of these presses, the box which contains the seed runs on a tramway in order to facilitate its removal from the heating-kettle, so that each time the bags have to be replenished the whole box has to be removed; and this causes no inconsiderable loss both of power and time, for it has, when filled, to be replaced on the ram and lifted bodily upwards in order to bring it flush with the top of the press, which fits the press-box and acts as a point of resistance. In this arrangement there are introduced only one press and one set of small pumps.

The next press we come to is Blundell's, which is admitted to be by far the most efficient in use to-day. Here there are two distinct presses, or a double hydraulic press, fed by two pumps, one 2-1/2 inches and the other 1 inch in diameter, both connected with the separate cylinders by hydraulic tubing. The stroke of these pumps is 5 inches, and they make thirty-six strokes a minute. The larger pump is weighted to 740 lbs. on the square inch, and the smaller to 5540 the square inch. The diameter of the rams is 12 inches, and the stroke 10 inches. Each press is fitted to receive four bags of seed, and it produces 64 lbs. of cake at each operation. After the heated seed has been placed in the bags, the attendant proceeds to fill one press, and then he opens the valve between the large pump and the charged press, which causes the ram to rise till there is a pressure of forty tons, whereupon the safety-valve of the large pump opens, and is kept so by a spring. While this operation is going on, the attendant is occupied with filling the second press; which completed, he opens the communication between the large pump and the second press, taking care first to replace the safety-valve. The ram of this press is then raised to the same height as the other, after which the safety-valve rises a second time. The attendant, as he closes the valve which opens the communication between the large pump and the press, at the same time opens the valve between the small pumps and the presses; and the pressure, amounting to about 300 tons, exerted by the small pump, is allowed to remain on the rams for about seven minutes. From which it appears that, allowing three minutes for emptying and charging the press, the process of expressing the oil takes only three minutes in all; and it is done by this press in this brief time in the most effectual manner. The oil, as it is expressed, passes through the canvas and hair bags to a cistern, known as the spill-tank, which is just large enough to contain the produce of one day's working. The presses are worked by oil instead of water, as it keeps both presses and pumps in better order. Each of them will produce 36 cwts. of cake per day of eleven hours, while the yield of oil is about 14 cwts. The oil is pumped from the spill-tanks to larger ones, capable of holding from 25 to 100 tons, where it remains for some time in order to settle previously to being brought to the market.

I do not intend to enter into the relative merits of the various presses, but content myself with having explained to you the manner in which the oil is produced.

Before concluding, it may be interesting to give you some idea of the vast extent of this manufacture. It appears, according to the official returns, that in the year 1841 we imported 364,000 quarters of seed.

THE OIL FROM LINSEED.

______________________________________________________ | 1842 | 368,000 | 1847 | 439,000 | 1852 | 800,000 | | 1843 | 470,000 | 1848 | 799,000 | 1853 | 1,000,000 | | 1844 | 616,000 | 1849 | 626,000 | 1854 | 828,000 | | 1845 | 666,000 | 1850 | 668,000 | 1855 | 757,000 | | 1846 | 506,000 | 1851 | 630,000 | 1856 | 1,100,000 | ______________________________________________________

Now if we take the last year's imports, we shall find that the produce would amount to about 144,000 tons' weight of oil-cake, and above 56,000 tons of oil.

The cake is used for feeding cattle, and the oil for burning, lubricating, painting, &c.; and a very large quantity is exported.

We find that to crush the seed imported in 1856 it required from 150 to 160 double hydraulic presses, nearly 100 of which were in Hull. This shows the extent of our commerce in the seed of flax, to say nothing of its fibre; and is one more instance of the great results which may be wrought out of little things. What a beautiful illustration of the bounty of Providence; and what an encouragement to the ingenuity of man! Who knows what treasures may yet lie hidden in neglected fields, or to what untold wealth the human family may one day fall heir?

_HODGE-PODGE: OR, WHAT'S INTILT._

WRITTEN NOV. 20, 1875, AT STAGENHOE PARK.

The subject and treatment, as well as title, of this Lecture are suggested by the answer of the hostess at a Scottish inn to an English tourist, who was inquisitive to know the composition of a dish which she offered him, and which she called Hodge-Podge. "There's water intilt," she said, "there's mutton intilt, there's pease intilt, there's leeks intilt, there's neeps intilt, and sometimes somethings else intilt." The analysis was an exhaustive one, and the intelligence displayed by the landlady was every way worthy of the shrewdness indigenous to her country; but her answer was not so lucid to her listener as to herself, as appeared by his bewildered looks, and his further half-despairing interrogatory. "But what is _intilt_?" said he, impatiently striking in before she had well finished. "Haven't I been tellin' ye what's intilt?" she replied. And she began the enumeration again, only with longer pause and greater emphasis at every step, as if she were enlightening a slow apprehension,--"There's water intilt, there's mutton intilt;" quietly and self-complacently adding, as she finished, "Ye surely ken now what's intilt." Whether her guest now understood her meaning, or whether he had to succumb, contented with his ignorance, we are not informed; but few of my readers need to be told that "intilt" is a Scotch provincialism for "into it," and that the landlady meant by using it to signify that the particulars enumerated entered as constituents _into_ her mysterious dish.

My aim is to discourse on the same constituents as they display their virtues and play their parts on a larger scale, in a wider economy; and when I have said my say, I hope I may be able to lay claim to the credit of having spoken intelligibly and profitably, though I must at the outset bespeak indulgence by promise of nothing more than the serving up of a dish of simple hodge-podge. The question I put in a wider reference is the question of the Englishman, as expressed in the Scotchwoman's dialect, What's intilt? and I assume that there enter into it, as radically component parts, at least the ingredients of this motley soup. Into the large hodge-podge of nature and terrestrial economics, as into this small section of Scotch cookery, there enter the element of water, the flesh of animals, and the fruits of the earth, as well as the processes by which these are brought to hand and rendered serviceable to life. The ingredients of hodge-podge exist in _rerum natura_, and the place they occupy and the function they fulfil in it are no less deserving of our inquisitive regard.

Thus, there is water in it, without which there were no seas and no sailing of ships, no rivers and no plying of mills, no vapour and no power of steam, no manufacture and no trade, and not only no motion, but no growth and no life. There is mutton, or beef, in it, and connected therewith the breeding and rearing of cattle, the production of wool, tallow, and leather, and the related manufactures and crafts. There are turnips and carrots in it, the latter of such value to the farmer that on one occasion a single crop of them sufficed to clear off a rent; and the former of such consequence in the fattening of stock and the provision of animal food, that a living economist divides society exhaustively into turnip-producing classes and turnip-consuming. There are leeks and onions in it, and these, with the former, suggest the art of the gardener, and the wonderful processes by which harsh and fibrous products can be turned into pulpy and edible fruits. And there are pease and barley in it, and associated therewith the whole art of the husbandman in the tillage of the soil and the raising of cereals, with the related processes of grinding the meal, baking the bread, preparing the malt, brewing the beer, and distilling the fiery life-blood at the heart.

Now, to discourse on all these, as they deserve, would be a task of no ordinary magnitude, but the subject is an interesting one, and to treat of it ever so cursorily might not unprofitably occupy a reflective moment or two. Water is the first topic it is laid upon me to talk about, and I begin with it all the more readily because it suggests a sense of freshness, and thoughts which may float our enterprise prosperously into port.

I. Water, as already hinted, is an element of vast account in the economy of nature, and is a recreation to the heart and a delight to the eye of both man and beast. To have a plentiful supply of it is one of the greatest blessings of God to the creature, and to be able to bestow it wisely and employ it usefully is one of the most serviceable of human arts. It is too valuable a servant to suffer to go idle, and many are the offices it might do us, if, as it travels from the mountains to the sea-board, we caught it in its course, harnessed it to our chariot, and guided it to our aim. We should turn it to account every inch of its progress, and compel it, as it can, to minister to our requirements by its irresistible energy. Its merely mechanical power is immense, and this is due in great part to its incompressibility; for it is in virtue of this quality alone we can, by means of it, achieve feats not otherwise feasible. How else could we have raised to its sublime height that stupendous bridge which spans the Menai Straits, and which is the wonder of the beholder, as it is the boast of the designer? It stands where it does by the help of some mechanism indeed, but the true giant that lifted it on his shoulders and bore it to its airy elevation was the incompressible force of water, a fluid which is, strangely, the simple product of the combination of two elastic transparent gases, oxygen and hydrogen, neither of which apart has the thew and sinew of its offspring. Nay, it is this single element, which, acted on by heat or acting through machinery, fetches and carries for us over the wide globe, and is fast weaving into one living web the far-scattered interests of the world.

Water was in primitive times utilised into a motive power by the help of a mechanism of rude design, which yet is hardly out of date, and might recently be seen in its original, still more in modified form, in certain back-quarters of civilisation. A stream, guided by a sluice, was made to play upon four vertical paddle-blades, attached to a shaft which they caused to revolve, and which moved a millstone, resting upon another through which it passed. It was a primitive mill, which superseded the still more primitive hand-mill, or quern; and I myself have seen it at work in the Shetland Islands, and even the north of Scotland, though it is now done away with even there, still more farther south, and its place supplied and its work done by overshot and under-shot wheel-gear, and improved machinery attached, of less or more complexity. One of the most recent improvements is the Turbine, a sort of Barker's mill; it is of great power, small compass, and acts under a good fall with a minimum expenditure of water-power.

Passing from the consideration of water as a motive power in its natural state, I ask you to notice briefly the gigantic force it can be made to develop under the action of heat. In its normal form the power of water is due, as I have said, to its incompressibility; in the state of vapour, to which it is reduced by heat, its power is due to the counter force of expansion. It was when confined as a state prisoner in the Tower of London that the Marquis of Worcester began to speculate on the possibilities of steam, though he little dreamed of its more important applications, and the incalculable services it might be made to render to the cause of humanity. Suddenly, one day, his musings in his solitude were interrupted by the rattling of the lid of a kettle, which was boiling away on the fire beside him, when, being of a philosophic vein, he commenced to inquire after the cause; and he soon reasoned himself into the conclusion that the motive power lay in the tension of the vapour, and that the maintenance of this must be due to successive additions of heat. The thought was a seed sown in a fit soil, for it led to experiments which confirmed the supposition, and inaugurated others that have borne fruit, as we see. It was a great moment in the annals of discovery, and from that time to this the genius of improvement has moved onward with unprecedented strides; and this in the application of steam-power as well as the results, stupendous as these last have been. For as there is no department of industry that has not made immense advances since, none on which steam has not directly or indirectly been brought to bear with effect; so there has been no end to the ingenuity and ingenious devices by which steam has been coaxed into subjection to human use and made the pliant minister of the master, man. All these results follow as a natural consequence from the first discovery of its motive power by the Marquis of Worcester, and the subsequent invention of James Watt, by which the force detected was rendered uniform, instead of fitful and spasmodic, as it had been before. And yet, important as was the discovery of the one, and ingenious as is the invention of the other, both are of slight account in the presence of the great fact of nature observed by the English nobleman and humoured by the Scottish artisan. The _genie_ whom the one captured and the other tamed, is the great magic worker, apart from whose subtle strength their ingenuity had been wasted, and had come to naught.