a short lever from the side to the centre. a horizontal beam is supported at its exThe strength, therefore, has relation to tremities, its weight bends it down more the difference between these. Shortness, or less in the middle, the particles on the then, or any stay or projection at the side upper side being compressed, while the of the pillar, which, by making the resist- parts below are distended; and the bending lever longer, opposes bending, really ing and tendency to break are greater, acincreases the strength of a pillar. A col- cording as the beam is longer and its umn with ridges projecting fro:n it is, on thickness or depth is less. The danger this account, stronger than one that is per- of breaking, in a beam so situated, is judgfectly smooth. A hollow tube of metal is ed of, by considering the destroying force stronger than the same quantity of metal as acting by the long lever reaching from in a solid rod, because its substance, the end of the beam to the centre, and the standing farther from the centre, resists resisting force or strength as acting only by with a longer lever. Hence pillars of cast, the short lever from the side to the centre, iron are generally made hollow, that they while only a little of the substance of the may have strength with as little metal as beam on the under side is allowed to resist possible. In the most perfect weighing- at all. This last circumstance is so rebeams for delicate purposes, that there markable, that the scratch of a pin on the may be the least possible weight with the under side of a plank resting as here suprequired strength, the arms, instead of be- posed, will sometimes suffice to begin the ing of solid metal, are hollow cones, in fracture. Because the resisting lever is which the metal is not much thicker than small in proportion as the beam is thinner, writing paper. Masts and yards for ships a plank bends and breaks more readily have been made hollow, in accordance than a beam, and a beam resting on its with the same principle. In nature's edge bears a greater weight than if resting works, we have to admire numerous il- on its side. Where a single beam cannot Justrations of the same class. The stems be found deep enough to have the strength of many vegetables, instead of being required in any particular case-as for round externally, are ribbed or angular supporting the roof of a house- several and fluted, that they may have strength to beams are joined together, and in a great

ia resist bending. They are hollow, also, as variety of ways, as is seen in house-rafters, in cornstalks, the elder, the bamboo of &c., which, although consisting of three tropical climates, &c., thereby combining or more pieces, may be considered as one lightness with their strength. A person very broad beam, with those parts cut out who visits the countries where the bam- which do not contribute much to the boo grows, cannot but admire the almost strength.—The arched form bears transendless uses to which its straightness, verse pressure so admirably, because, by lightness and hollowness, make it appli- means of it, the force that would destroy, cable among the inhabitants. Being found is made to compress all the atoms or parts of all sizes, it has merely to be cut into at once, and nearly in the same degree. pieces of the lengths required for any pur- The atoms on the under side of an arch, pose ; and nature has already been the resting against immovable abutments, turner, and the polisher, and the borer, must be compressed about as much as &c. In many of the Eastern islands, those on the upper side, and cannot therebamboo is the chief material of the ordi- fore be torn or overcoine separately. The nary dwellings, and of the furniture,--the whole substance of the arch, therefore, refanciful chairs, couches, beds, &c. Flutes sists, almost like that of a straight pillar and other wind instruments there are under a weight, and is nearly as strong. nerely pieces of the reed, with holes bor- To be able to adapt the curve to the size ed at the requisite distances. Conduits for of an arch, and to the nature of the matewater are pipes of bamboo; bottles and rial, requires in the architect a perfect accasks for preserving liquids are single quaintance with measures, &c. An error joints of larger bamboo, with their parti- which has been frequently committed by tions remaining; and bamboo, split into bridge-builders is, the neglecting to conthreads, is twisted into rope, &c. From sider sufficiently the effect of the horizon-. the animal kingdom, also, we have illus- tal thrust of the arch on its piers. Each trations of our present subject—the hol- arch is an engine of oblique force, pushlow stiffness of the quills of birds; the hol- ing the pier away from it. In some inlow bones of birds; the bones of animals stances, one arch of a bridge falling, has generally, strong and hard, and often an- allowed the adjoining piers to be pusheel gular externally, with light cellular texture down towards it, by the thrust, no longer within, &c.— I'ransverse Pressure. When balanced, of the arches beyond, and the

whole structure has given way at once, common egg-shell is another example of like a child's bridge built of cards. It is the same class : what hard blows of the pot known at what time the arch was in- spoon or knife are often required to penevented, but it was in comparatively modern trate this wonderful defence provided for times. The hint may have been taken from the dormant life! The weakness of a nature ; for there are instances, in alpine similar substance, which has not the countries, of natural arches, where rocks arched form, is seen in a scale from a have fallen between rocks, and have there piece of freestone, which so readily crumbeen arrested and suspended, or where bles between the fingers. To determine, burrowing water has at last formed a wide for particular cases, the best forms of passage under masses of rock, which re- beams and joists, and of arches, domes, main balanced, among themselves, as an &c., is the business of strict calculation, arch above the stream. Nothing can sur- and belongs, therefore, to mathematics, or pass the strength and beauty of some the science of measures. It was a beaumodern stone bridges—those, for instance, tiful problem of this kind, which Mr. which span the Thames as it passes Smeaton, the English engineer, solved se through London. Iron bridges have been perfectly in the construction of the farmade with arches twice as large as those famed Eddystone light-house. (See Lightof stone, the material being more tena House.) cious, and calculated to form a lighter STRENGTH, FEATS OF. Doctor Brewswhole. That of three fine arches, between ter, in his work on Natural Magic, gives the city of London and Southwark, is a some striking instances of muscular noble specimen; and, compared with the strength, and also of the effects produced bridges of half a century ago, it appears by applying the principles of the mechanialmost a fairy structure of lightness and cal powersto the human frame, from which grace. The great domes of churches, as we extract the following :-Firmus, a uathose of St. Peter's in Rome and St. Paul's tive of Seleucia, who was executed by in London, have strength on the same the emperor Aurelian for espousing the principle as simple arches. They are, cause of Zenobia, was celebrated for his in general, strongly bound at the bottom feats of strength. In his account of the with chains and iron bars, to counteract life of Firmus, who lived in the third the horizontal thrust of the superstructure. century, Vopiscus informs us, that he The Gothic arch is a pointed arch, and is could suffer iron to be forged upon an calculated to bear the chief weight on its anvil placed upon his breast. In doing summit or key-stone. Its use, therefore, this, he lay upon his back, and, resting his is not properly to span rivers as a bridge, feet and shoulders against some support, but to enter into the composition of varied his whole body formed an arch, as we pieces of architecture. With what effect shall afterwards more particularly explain. it does this, is seen in the truly sublime Until the end of the sixteenth century, the Gothic structures which adorn so many exhibition of such feats does not seem to parts of Europe. The following are in- have been common.

About the year stances, in smaller bodies, of strength ob- 1703, a native of Kent, of the name of tained by the arched form : Athin watch- Joyce, exhibited such feats of strength in glass bears a very hard push ; a dished or London and other parts of England, that arched wheel for a carriage is many times he received the name of the second Samstronger to resist all kinds of shocks than son. His own personal strength was very a perfectly flat wheel; a full cask may fall great; but he had also discovered, with. with impunity where a strong square box out the aid of theory, various positions would be dashed to pieces; a very thin of the body, in which men even of comglobular flask or glass, corked and sent mon strength could perform very surdown many fathoms into the sea, will resist prising feats. He drew against horses, the pressure of water around it

, where a and raised enormous weights ; but as he square bottle, with sides of almost any actuallyexbibited his power in ways which thickness, would be crushed to pieces. evinced the enormous strength of his own We have an illustration, from the animal muscles, all his feats were ascribed to the frame, of the arched form giving strength, same cause. In the course of eight or in the cranium or skull, and particularly ten years, however, his methods were in the skull of man, which is the largest discovered, and many individuals of orin proportion to its thickness: the brain dinary strength exhibited a number of his required the most perfect security, and, principal performances, though in a manby the arched form of the skull, this has ner greatly inferior to Joyce. Some time been obtained with little weight. The afterwards, John Charles van Eckeberg,

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VOL. XIII.

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a native of Harzgerode, in Anhalt, trav- rising up and down while the performer elled through Europe, under the appella- breathed. A stone one and a half feet tion of Samson, exhibiting very remarka- long, one foot broad, and half a foot thick, ble examples of his strength. This, we was then laid upon his belly and broken believe, is the same person whose feats by a sledge-hammer an operation which are particularly described by doctor De was performed with much less danger saguliers. He was a man of the middle size, than when his back touched the ground. and of ordinary strength; and, as doc- 5. His next feat was to lie down on the tor Desaguliers was convinced that his ground. A man being then placed on feats were exhibitions of skill, and not of his knees, he drew his heels towards his strength, he was desirous of discovering body, and, raising his knees, he lifted up his methods; and, with this view, he went the man gradually, till, having brought his to see him, accompanied by the marquis knees perpendicularly under him, he raised of Tullibardine, doctor Alexander Stuart, his own body up, and, placing his arms and doctor Pringle, and his own mechan- around the man's legs, rose with him, ical operator. They placed themselves and set him down on some low table or round the German so as to be able to ob- eminence of the same height as his knees. serve accurately all that he did; and their This feat he sometimes performed with success was so great, that they were able two men in place of one. 6. In his last, to perform most of the feats the same and apparently most wonderful performevening by themselves, and almost all the ance, he was elevated on a frame work, and rest when they had provided the proper supported a heavy cannon placed upon a apparatus. Doctor Desaguliers exhibited scale at some distance below him, which some of the experiments before the royal was fixed to a rope attached to his girdle. society, and has given such a distinct ex- Previous to the fixing of the scale to the planation of the principles on which they rope attached to his girdle, the cannon depend, that we shall endeavor to give a and scale rested upon rollers; but when all popular account of them. 1. The perform- was ready, the rollers were knocked away, er sat upon an inclined board with his feeta and the cannon remained supported by little higher than his hips. His feet were the strength of his loins. These feats may placed against an upright board well se- be briefly explained thus:-The feats No. cured. Round his loins was placed a 1, 2 and 6, depend entirely on the natural strong girdle with an iron ring in front. strength of the bones of the pelvis, which To this ring a rope was fastened. The form a double arch, which it would rerope passed between his legs through a quire an immense force to break, by any hole in the upright board, against which external pressure directed to the centre his feet were braced, and several men or of the arch; and as the legs and thighs two horses, pulling on the rope, were una- are capable of sustaining four or five ble to draw him out of his place. 2. He thousand pounds when they stand quite also fastened a rope to a high post, and, upright, the performer has no difficulty having passed it through an iron eye fixed in resisting the force of two horses, or in the side of the post some feet lower in sustaining the weight of a cannon down, secured it to his girdle. He then weighing two or three thousand pounds. planted his feet against the post near the The feat of the anvil is certainly a very iron eye, with his legs contracted, and, surprising one. The difficulty, however, suddenly stretching out his legs, broke really consists in sustaining the anvil; for the rope, and fell backwards on a feather when this is done, the effect of the hambed. 3. In imitation of Firmus, he laid mering is nothing. If the anvil were a himself down on the ground, and when thin piece of iron, or even two or three an anvil was placed upon his breast, a times heavier than the hammer, the perman hammered with all his force a former would be killed by a few blows; piece of iron, with a sledge-hammer, but the blows are scarcely felt when the and sometimes two smiths cut in two anvil is very heavy, for the more matter with chisels a great cold bar of iron laid the anvil has, the greater is its inertia, upon the anvil. At other times, a stone and it is the less liable to be struck out of of huge dimensions was laid upon his its place; for when it has received by the helly, and broken with a blow of the great blow the whole momentum of the hamhammer. 4. The performer then placed mer, its velocity will be so much less his shoulders upon one chair, and his than that of the hammer as its quantity heels upon another, forming with his of matter is greater. When the blow, inback-bone, thighs and legs, an arch. One deed, is struck, the man feels less of or two men then stood upon his belly, the weight of the anvil than he did before, because, in the reaction of the stone, teeth, and held in a horizontal position for all the parts of it round about the ham- a considerable time, a table six feet long, mer rise towards the blow. This prop- with half a hundred weight hanging at erty is illustrated by the well-known ex- the end of it. The feet of the table restperiment of laying a stick with its ends up- ed against his knees. 6. Holding in his on two drinking glasses full of water, and right hand an iron kitchen poker three feet striking the stick downwards in the mid- long and three inches round, he struck dle with an iron bar. The stick will in upon his bare left arm, between the elbow this case be broken without breaking the and the wrist, till he bent the poker pearglasses or spilling the water. But if the ly to a right angle. 7. Taking a similar stick is struck upwards as if to throw it poker, and holding the ends of it in his up in the air, the glasses will break if the hands, and the middle against the back blow be strong, and if the blow is not of his neck, he brought both ends of it very quick, the water will be spilt with- together before him; and he then pulled it out breaking the glasses. When the almost straight again. This last feat was performer supports a man upon his belly, the most difficult, because the muscles he does it by means of the strong arch which separate the arms horizontally formed by his back-bone and the bones of from each other, are not so strong as his legs and thighs. If there were room those which bring them together. 8. He for them, he could bear three or four, or, broke a rope about two inches in circumin their stead, a great stone, to be broken ference, which was partly wound about a with one blow. A number of feats of cylinder four inches in diameter, having real and extraordinary strength were ex- fastened the other end of it to straps thai hibited about a century ago, in London, went over his shoulder. 9. Doctor Desaby Thomas Topham, who was five feet guliers saw him lift a rolling stone of about ten inches high, and about thirty-one 800 pounds weight with his hands only, years of age. He was entirely ignorant standing in a frame above it, and taking of any of the methods for making bis hold of a frame fastened to it. Hence strength appear more surprising; and he doctor Desaguliers gives the following often performed by his own natural powers relative view of the strengths of indiwhat he learned had been done by others viduals. by artificial means. A distressing example of this occurred in his attempt to imitate

Strength of the weakest men, 125 lbs. the feat of the German Samson by pull

Strength of very strong men, · 400ing against horses. Ignorant of the meth

Strength of Topham, od which we have already described, he The weight of Topham was about 200 lbs. seated himself on the ground, with his One of the most remarkable and infeet against two stirrups, and by the explicable experiments relative to the weight of his body he succeeded in pull- strength of the human frame, is that in ing against a single horse ; but in attempt- which a heavy man is raised with the ing to pull against two horses, he was greatest facility, when he is lifted up the lifted out of his place, and one of his instant that his own lungs and those of knees was shattered against the stirrups, the persons who raise him are inflated so as to deprive him of most of the with air. The heaviest person in the strength of one of his legs. The follow- party lies down upon two chairs, his legs ing are the feats of real strength which being supported by the one and his back doctor Desaguliers saw him perform.- by the other. Four persons, one at each 1. Having rubbed his fingers with coal leg, and one at each shoulder, then try to ashes to keep them from slipping, he roll- raise him; and they find his dead weight ed up a very strong, and large pewter to be very great, from the difficulty they plate. 2. Having laid seven or eight experience in supporting him. When he is short and strong pieces of tobacco-pipe replaced in the chair, each of the four on the first and third finger, be broke persons takes hold of the body as before, them by the force of his middle finger. and the person to be lifted gives two sig. 3. He broke the bowl of a strong tobacco- nals by clapping

his hands. At the first pipe, placed between his first and third signal, he himself and the four lifters befinger, by pressing his fingers together gin to draw a long and full breath ; and sideways. 4. Having thrust such an- when the inhalation is completed, or the other bowl under his garter, his legs lungs filled, the second signal is given for being bent, he broke it to pieces by the raising the person from the chair. To tendons of his hams, without altering the his own surprise and that of his bearers, bending of his leg. '5. He lifted with his he rises with the greatest facility, as if he

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