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hypotheses of either system, we are persuaded, a
theory of dreaming, if not perfectly satisfactory,
at least less exceptionable than any of the above,
may be drawn from merely attending to a simple
fact that frequently takes place when we are
awake. Every person must have observed, that
when alone, and while his attention is not called
to any particular subject, either by study, con-
versation, manual labor, sudden noise, or the
objects around him, a kind of involuntary mo-
tion, so to speak, will take place in his ideas;
and that, if he makes no voluntary exertion of
mind to fix his attention upon one idea more
than another, a rapid succession of very different
ideas, some old and some recent, will occur in
the course of a few minutes. Every person,
who attends church regularly, or who has at-
tended the lectures of an unentertaining public
speaker, must be sensible, that such involuntary
notions of his ideas have often taken place,
when, either through the fault of the speaker, or
that of the hearer, his attention has not been
sufficiently fixed upon what was spoken. A
person much addicted to study, and to the habit
of fixing his ideas constantly upon one subject
or another, may, perhaps, be less sensible of the
involuntary motion we here allude to, than
others; but let such a studious person be placed
in a company where a trifling conversation is
going on, and he will soon find himself in the
situation here described. A current of ideas will
rapidly intrude upon his mind, and carry off
his attention from the trifles in which those around
him are engaged; and thus subject him to what
is commonly called absence of mind. And it
will also be admitted that the most studious, as
well as the most thoughtless, will sometimes find
an idea of a long forgotten fact, sentiment, or
circumstance, suddenly recurring to their minds,
without any seeming cause. The inference we
would draw from all these facts, to our present
subject, is, that during sleep, a similar involun-
tary motion, or current of ideas, takes place;
but that, in consequence of the fatigue occasioned
by the labors of the day (no matter whether these
operate by exhausting the excitability, or by oc-
casioning a deficiency of the nervous fluid), the
three chief powers of the mind-the will, the
judgment, and the memory, are rendered in a
considerable degree inactive; at least, in so far,
that the will has no power over these faculties,
while the imagination, rendered more active, as
it would seem, by being freed from the control
of both the will and the judgment, gives every
new idea that occurs a visionary form; and thus
creates a fresh and rapid succession of various
images, according to the unlimited current of
uncontrolled ideas that succeed each other. How
this happens, perhaps, the human faculties will
never be able to comprehend or explain; at least,
till they shall be capable of explaining the con-
nexion by which the soul and body are united,
if, indeed, mankind shall ever attain to such a
degree of perfection in physiology. But that
dreams take their rise chiefly, if not solely, from
the mere succession of ideas, dressed into form
by the imagination, uncontrolled by the will or
the judgment, appears to us to be an undoubted
fact, though hitherto it would seem little, if at

all, attended to. And it appears to be a suffi cient confirmation of this theory, that persons in good health, and engaged in active employments, most commonly dream of those matters wherein they are daily occupied; the uniform current of their ideas when awake, seldom taking any other direction during sleep; whereas, persons in a bad habit of body, or weak state of mind, and those who take little exercise, or who are not engaged in active business, have generally wild and extravagant dreams, and sometimes very disagreeable ones, of monsters, mad dogs, devils, deep pits, houses on fire, stormy oceans, and the like. In a word, when we consider the operations of our minds when awake, particularly of that active faculty, the imagination, how readily upon hearing, reading, or speaking of any person, place, action, or circumstance, it forms an idea in the mind of such person, place, &c., though, perhaps, many years have elapsed since we saw them, or even though we have never seen them, we need not be surprised, that the same active faculty should be able, when uncontrolled by the will and judgment, and but partially assisted by the memory, to raise up a series of images in succession, and thus to create an ideal world, and various ideal transactions in the mind.

The late Mr. Rennell, of Kensington, considers dreams to afford satisfactory proof that the mind can act without the intervention of the brain: upon this it has been well remarked, that we have not as yet sufficient data from which to estimate the degree of dependence of the former. upon the latter, still we have no facts founded upon our present state of being, which can establish the total independence which he supposes. The proximate cause of sleep is undoubtedly corporeal, and, perhaps, consists in a certain inaptitude of the brain to receive the usual impulses of its immaterial tenant. When this inaptitude amounts to complete quiescence, the soul cannot display itself, because the instrument of its operations is in a state of repose. In such circumstances the sleep is profound, and no dreams take place. This repose or quiescence of the brain may be increased to absolute torpor for a season, as is seen in the hybernation of animals, and in those rare cases in the human species, where persons have remained for several hours, or even days, in a trance. When this torpor of the cerebral system abates, the immaterial principal is again enabled to resume its operations, owing to the renewed capabilities of the instrument. Thus, as the cause of sleep is corporeal, there are strong grounds for presuming that the cause of dreams is corporeal also. They occur oftenest when there is any irritation of the system in general, or of the brain in particular, hindering the complete repose of that part. When this irritation is great, as in general fever, accompanied with increased action of the blood-vessels within the head, sleep is often entirely prevented; or if it does take place, it is disturbed with frightful illusions. What is the precise state of the soul at such times, is a disputed point amongst metaphysicians. Perhaps, on so dark a subject, it may be allowable to hazard a conjecture, that the operations of the immaterial being are modified by the semi

quiescence of the material organ, and that this want of correspondence between the agent and the instrument is the cause of the wild imaginations and false judgments that distinguish our dreams from our waking thoughts. Dreams, therefore, instead of proving the contrary, rather tend to show that the dependence of the immaterial upon the material part is perpetual and without exception, during the continuance of man's existence upon earth.

In whatever way we attempt to account for the manner, in which our powers of mind and body perform their functions in dreaming, we can, at least, apply to useful purposes the imperfect knowledge which we have been able to acquire concerning this series of phenomena. Our dreams are affected by the state of our health, by the manner in which we have passed the preceding day, by our general habits of life, by the hopes which we most fondly indulge, and the fears which prevail most over our fortitude when awake. From recollecting our dreams, therefore, we may learn to correct many improprieties in our conduct; to refrain from bodily exercises, or from meats and drinks that have unfavorable effects on our constitution; to resist, in due time, evil habits that are stealing upon us; and to guard against hopes and fears which detach us from our proper concerns, and unfit us for the duties of life. Instead of thinking what our dreams may forebode, we may, with much better reason, reflect by what they have been occasioned, and look back to those circumstances in our past life, to which they are owing. The sleep of innocence and health is sound and refreshing; their dreams delightful and pleasing. A distempered body, and a polluted or perturbed mind, are haunted in sleep with frightful, impure, and unpleasing dreams. The reader who is disposed to speculate farther on this subject, may consult Dr. Beattie's Essays, Hartley on Man, and the principal writers on physiology. We may add, some very beautiful fables have been written both by ancients and moderns in the form of dreams. The Somnium Scipionis is one of the finest of Cicero's compositions. In the periodical publications, which have diffused so much elegant and useful knowledge through Great Britain, the Tatlers, Spectators, Guardians, &c., we find a number of excellent dreams. Addison excelled in this way of writing. The public are now less partial to this species of composition than formerly. Dr. Beattie, in his valuable Essay on Dreaming, quotes a very fine one from the Tatler, and gives it due praise. DREAR, adj. & n. s. DREARY, adj. DREAR'IHEAD, N. S. DREAR'IMENT, DREARINESS.

Sax. dreorig; Belg. treuer; from Goth.verb rygga, to lament. All the substantives signify sorrow, united with fear: drear and dreary are, dismal; mournful;

fearful.

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So with his dread Caduceus Hermes led
From the dark regions of the imprisoned dead,
Or drove in silent shoals the lingering train
To night's dull shore, and Pluto's dreary reign.
Darwin.

It struck even the besiegers' ear
With something ominous ani drear,
An undefined and sudden thrill,
Which makes the heart a moment still.
Byron.

O luxury!
Bane of elated life, of affluent state,
What dreary change, what ruin, is not thine? Id.
DREDGE, v. a. & n. s. Į Sax. drægan, to
DREDGER, n. s.
drag, of which word
(or of dregs?) this word is a corruption. To ga-
ther into a particular kind of net: the net used:
a dredger is one who uses such a net; and, per-
haps from its net-like top, a box for scattering
flour on meat, or amongst pastry; called also a
dredging-box.

For oysters they have a peculiar dredge; a thick,

strong net, fastened to three spills of iron, and drawn

at the boat's stern, gathering whatsoever it meeteth lying in the bottom. Carew.

The oysters dredged in the Lyne find a welcome acceptance.

Id.

DREDGING, in civil engineering, is the art of removing mud, silt, or other depositions from the bed of rivers, canals, harbours, or docks; and is accomplished by various tools and descriptions of machinery.

The common dredging-boat or barge is worked by two or more men, by whom the gravel, or ballast, is taken up in a leather bag, the month of which is extended by an iron hoop, attached to a pole, of sufficient length to reach the bot tom: in the small way, two men are employed to work each pole. The barge being moored, one of the men takes his station at the stern, with the pole and bag in his hand, the other stands in the head, having hold of a rope, tied fast to the hoop of the leather bag. The man at the stern now puts the pole and bag down, over the barge's side, to the bottom, in an inclined position. The hoop being farthest from the man in the head of is fast to the gunwale of the barge, he passes it the barge, and having a rope, one end of which twice or thrice round the pole, and then holds it tight: the man in the head now pulls the rope, fastened to the hoop, and draws the hoop and bag along the ground, the other allowing the pole to slip through the rope as it approaches the vertical position, at the same time causing such a friction, that the hoop digs into the ground, the leather bag receiving whatever passes through the

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hoop: both men now assist in getting a bag into the barge, and delivering its contents. When the bag is large, several men are employed; and, to increase the effect, a windlass, with wheel-work, is sometimes used. A chain or rope is brought to the winch from the spoon, through a block suspended from a small crane for bearing the spoon and its contents to the side of the boat, and bringing it over the gunwale to be emptied into it. The purchase rope is led upon deck by a snatch block in the proper direction for the barrel of the winch. From two to four men, can with this simple apparatus, lift from twenty to sixty tons in a tide, from a depth of from two and a half to three fathoms, when the ground is favorable. In this manner the convicts at Woolwich upon the Thames, have been long employed to perform the ballast-heaving, or dredging.

The bucket dredging-machine, whether worked by men, horses, or the steam-engine, is a great improvement on the above. The frame-work consists of two beams of timber, supported on a rod of iron with shores of wood; on these the full buckets move upon iron rollers fixed to the timber, while the empty buckets, attached to and guided by an endless chain, form a curve in descending to the bottom; as they respectively arrive they are intended to excavate or scoop up the silt or gravel from the ground. The operation of lowering and raising the frame once performed by crane-work, distinct from the machinery of the steam-engine, is now also accomplished by a power taken from it.

Plate DREDGING MACHINES, AA, fig. 1, is a frame of timber bolted to the starboard gunwale, to support a large horizontal beam BB, fig. 2; another similar frame is fixed up in the middle of the ship at D, fig. 2, and the end of the beam is sustained by an upright post bolted to the opposite gunwale; the starboard end of the beam projects over the vessel's side, and has an iron bracket S fastened to it, to support one of the bearings for the long frame E E, composed of four timbers bolted together: the other end of the frame is suspended by pulleys a, a; from a beam F fixed across the stern, the upper ends of the outside beams of the frame EE have each a stout iron bolted to them, which are perforated with two large holes to receive two short cast iron tubes, one fastened to the iron bracket S at the end of the beam B, and the other to a cross beam of the frame A; these tubes act as the pivots of the frame E, upon which it can be raised or lowered by the pulleys a, a: they also contain bearings for an iron axis, on which a wheel or trundle O is fixed, containing four rounds. Another similar trundle P is placed at the bottom of the frame EE, and two endless chains k,k, pass round both, as is seen in the plan. Between every other link of the two chains, a bucket of plate iron bbb is fastened, and, as the chain runs round, the buckets bring up the soil; a number of cast iron rollers d, d, are placed between the beams of the frame to support the chain and buckets as they roll up. Four rollers e,e, are also placed on each of the outside beams, to keep the chains in their places on the frame, that they may not get off to one side. The motion is conveyed to the chains by

means of a cast iron wheel at G in the plan, wedged on the end of the axis of the upper trundle O. The wheel is cast hollow, like a very short cylinder, and has several screws tapped through its rim, pointing to the centre, and pressing upon the circumference of another wheel enclosed within the hollow of the first, that it may slip round in the other, where any power greater than the friction of the screw is applied; the internal wheel is wedged on the same shaft with a large cog-wheel f, turned by the small cog-wheel g, on the axis of the steam-engine. The steam-engine is one of that kind called high pressure, working by the expansive force of the steam only, without condensation; h is the boiler containing the fire-place and cylinder within it; i is one of the connecting rods, and the fly wheel on the other end of the same shaft as the wheel g. The pulleys a, which suspend the chain frame, are reeved with an iron chain, the tackle fall of which passes down through the ship's deck, and is coiled on a roller m in the plan, and represented by a circle in the elevation on the end of the roller is a cog-wheel p, turned by the engine wheel g: the bearing of this wheel is fixed upon a lever, one end of which comes near that part of the steam-engine, where the cock, which regulates the velocity of the engine, is placed; so that one man can command both lever and cock, and, by depressing that end of the lever, cause the wheel p to geer with g, and consequently be turned thereby, and wind up the chain of the pulleys; g is a strong curved iron bar bolted to the vessel's side and gunwale, passing through an eye bolted to the frame E, to keep the frame to the vessel's side, that the tide or other accident may not carry it away.

A hopper or trough is suspended beneath the wheel o, by ropes from the beam B, into which the buckets b, b, b, empty the ballast they bring from the bottom; the hopper conveys it into a barge brought beneath it; this hopper is not shown in the plate, as it would tend to confuse parts already not very distinct. The motion of the whole machine is regulated by one man. The vessel being moored fast, the engine is started, and turns the chain of buckets: the engine tender now puts his foot upon a lever, disengages the wheel p from g, and by another takes off a gripe which embraced the roller m. This allows the end E of the frame to descend, until the buckets on the lower half of the chain drag on the ground, as shown in fig. 1, when he stops the further descent by the gripe, the buckets are filled in succession at the lower end of the frame, and brought up to the top, where they deliver their contents into the hopper before-mentioned: as they take away the ballast from the bottom, the engine tender lets the frame E down lower by means of the gripe lever, and keeps it at such a height that the buckets come up nearly full; if at any time the buckets get such deep hold as to endanger the breaking of the chain or stopping the engine, the coupling-box at G before-described, suffers the steam-engine to turn without moving the chain of buckets, and the engine tender, pressing his foot upon the lever which brings the wheel p to geer with g, causes the roller n to be turned by the engine, and raise up the frame E, until

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