BEES. bees to remove all extraneous matter, and to defend themselves from robbers and intruders. The entrance to the hive is about three inches wide, and half an inch high. A door of wire, the meshes of which are small enough to prevent the entrance of the miller, rests behind two door posts made of needles. These needles are driven into the floor, close to the entrance. The little doors are always put behind the needles as soon as the bees are in for the night, and are removed at day light. About the middle of April the doors are first used, and they are discontinued in about two months. "After the middle of June the floors are let down, and are suffered to hang until day light, when they are gently raised and hooked up. The floor of the hive projects in front about three inches, thus forming an apron or platform, on which the bees alight before they enter in at the little door." BEE MOTH. This is the great foe of the honey bee-one which neither the instinctive powers of self preservation, with which the bee is endued, is able to resist, nor the ingenuity and skill of man are able effectually to provide against. And to the depredations of this single enemy is to be attributed the indifference which obviously prevails as to attempts, on an extended scale, to foster this industrious race. We are among those who entertain the belief that no effectual remedy will soon be found for the evil here alluded to; at least none which will admit of so universal and easy application, as to induce any great numbers in our land to turn their attention to the cultivation of bees. Still something may be done. Before proceeding to the few suggestions which we design to make, a brief description of the bee moth may be proper. It appears in the form of a small miller, of a grayish color, pale towards the head, of a glossy brown near the outer margin of the wings. It has four wings, but is little disposed to fly much. It begins to molest bees about the middle or last of April, and continues its persecutions till September. Its depredations are chiefly committed towards the close of the day, and during the night. Their eggs are deposited either in the hive itself, or in the crevices around about it. These eggs are hatched in a few weeks, and produce a grub or worm with a reddish head, which finds its way into the hive, where, having fortified itself by means of a web, it feeds upon the wax, comb, eggs, and young brood of bees, and continues to extend its ravages with a Goth and Vandal spirit, until the whole internal establishment becomes one wide-spread desolation. To prevent entirely the depredations of these enemies is probably impossible. Their injurious effects, however, may in a measure be prevented by destroying the millers, which may be effected in a degree by placing open shallow vessels near the hives containing sweetened water and vinegar. By sipping this liquor, of which they are fond, they become intoxicated and drown. Some recommend to sprinkle spirits of turpentine round the hives; others recommend closing the entrance of the hive, after the ingress of the bees, and opening it early in the morning. It has been suggested by a respectable writer, to place the hives on the naked ground, or which is thought still better, to cover the floor of the bee-house with earth about two inches in depth. This last method is recommended by way of experiment, by Dr. Thach LOCOMOTION. er, in the work to which we have already alluded, and to which we would refer our readers for other important hints on this particular topic, as well as for numerous suggestions in reference to the general management of bees. PART VII. ARTS OF LOCOMOTION—OF HEATING, VENTILATION, &c. LOCOMOTION. MOTION OF ANIMALS. "The chief obstacles which oppose locomotion or change of place," says Dr. Bigelow,*" are gravity and friction, the latter of which is in most cases, the consequence of the former. Friction is obviated by animals that walk, by substituting points of their bodies instead of large surfaces, and upon these points they turn, as upon centres, for the length of each step, raising themselves wholly or partly from the ground in successive arcs, instead of drawing themselves along the surface. The line of arcs which the centre of gravity describes, is converted into an easy or undulating line, by the compound action of the different joints! As the feet move in separate lines, the body has also a lateral, vibratory motion. A man, in walking, puts down one foot before the other is raised, but not in running. Quadrupeds in walking have three feet upon the ground for most of the time; in trotting, only two. Animals which walk against gravity, as the common fly, the tree toad, &c., support themselves by suction, using cavities on the under side of their feet, which they enlarge at pleasure, till the pressure of the atmosphere causes them to adhere. In other respects their locomotion is effected like that of other walking animals. Birds perform the motion of flying by striking the air with the broad surface of the wings in a downward and backward direction, thus propelling the body upward and forward. After each stroke the wings are contracted, or slightly turned, to lessen their resistance to the atmosphere, then raised and spread anew. The downward stroke also, being more sudden than the upward, is more resisted by the atmosphere. The tail of birds serves as a rudder to direct the course upward or downward. When a bird sails in the air without moving the wings, it is done in some cases by the velocity previously acquired, and an oblique direction of the wings upward;—in others, by a gradual descent, with the wings slightly turned in an oblique direction downward. Fishes, in swimming forward, are propelled chiefly by strokes of the tail, the extremity of which being bent into an oblique position, propels the body forward and laterally at the same time. The lateral motion is corrected by the next stroke, in the opposite direction, while the forward course continues. The fins serve partly to assist in swimming, but chiefly to balance the body, or keep it upright; for the centre of gravity being * Elements of Technology, p. 192 LOCOMOTION. nearest the back, a fish turns over, when it is dead, or disabled.* Some other aquatic animals, as leeches, swim with a sinuous or undulating motion of the body, in which several parts at once are made to act obliquely against the water. Serpents in like manner advance by means of the winding or serpentine direction which they give to their bodies, and by which a succession of oblique forces are brought to act against the ground. Sir Everard Home is of opinion that serpents use their ribs in the manner of legs, and propel the body forwards by bringing the plates on the under surface of the body to act successively like feet against the ground. Some worms and larvæ of slow motion, extend a part of their body forwards, and draw up the rest to overtake it, some performing this motion in a direct line, others in curves. "When land animals swim in water, they are supported, because their whole weight, with the lungs expanded with air, is less than that of an equal bulk of water. The head, however, or a part of it, must be kept above water to enable the animal to breathe, and to effect this and also to make progress in the water, the limbs are exerted in successive impulses against the fluid. Quadrupeds and birds swim with less effort than man, because the weight of the head, which is carried above water, is, in them, a smaller proportional part of the whole, than it is in man." HUMAN STRENGTH, or Power. Desaguilliers states that the power of a man, applied in various ways, will produce the following results: A man can raise by a good common pump, a hogshead-63 galls.of water 10 feet high in a minute, for a whole day. A man of ordinary strength can turn a winch with a force of 30 pounds, and with a velocity of 34 feet in a second, for 10 hours a day. Two men working at a windlass with handles at right angles, can raise 70 lbs. more easily than one can raise 30. According to Mr. Buchanan's comparison, the force exerted in turning a winch being made equal to the unit, or standard, The force as in pumping will be .61 as in ringing, = 1.36 1.43 Porters are commonly able to carry from 200 to 300 pounds at the rate of 3 miles an hour. By a careful adjustment of the weight low upon the hips, it is stated that Porters are able to move forward under a load of from 700 to 900 lbs. Coulomb observes that the most advantageous weight, for a man of common strength to carry horizontally, is 111 pounds; or if he re * The swimming bladder which exist in most fishes, though not in all, is supposed to have an agency in adapting the specific gravity of the fish to the particular depth in which it resides. The power of the animal to rise or sink by altering the dimensions of this organ, has been, with some reason, disputed. + Lectures on Comparative Anatomy, vol. i. p. 116, &c. Sir E. Home deduces this fact from the anatomy of the animal, and from the movements which he perceived, in suffering a large coluber to crawl over his hand. The ribs appeared to be raised, spread, carried forward, depressed and pushed backward, successively. Allen's Mechanics, p. 150. AIDS TO LOCOMOTION. turn unladen, 135 pounds. With wheel-barrows men will do half as much more work as with hods, as in the mode previously mentioned. Surprising accounts are given of the strength of men to sustain weights of above 2000 lbs. by means of proper apparatus adjusted to the hips. The weights, however, in the cases stated, do not appear to have been sustained by muscular strength, but merely by placing the legs in the most favorable perpendicular position, whereby the bones receive the whole stress, with but little more muscular exertion than is required for maintaining them in an erect posture. The bones of the legs and the arch of the pelvis, although apparently so frail in form and texture, are constructed with such admirable science that it is supposed by anatomists they might sustain a weight of nearly 4000 pounds. AIDS TO LOCOMOTION. Although the bodily strength of man, according to the preceding article, would enable him to accomplish much, without mechanical contrivance; yet it is easy to perceive that independent of that contrivance but little comparatively could be effected either as to moving himself, or conveying the more ponderous articles of commerce, great distances, in any moderate space of time. The aids to locomotion, discovered by the ingenuity of man are quite numerous. We shall find room to notice but a few, and those quite briefly. WHEELS. Wheels are designed to diminish friction, and also to surmount obstacles or inequalities of the road, with more advantage than bodies of any other form in their place could do. The friction being transferred from the surface of the gronnd to the centre of the wheel, is lessened in the proportion, which the diameter of the axletree bears to the diameter of the wheel. The rubbing surfaces, also, being polished and oiled, are in the best possible condition to resist friction. The best composition for diminishing friction is said to be common soapstone or steatite reduced to powder and mixed with oil. One part of black lead to three parts of lard forms also a good anti-attrition compound. The principle upon which a wheel easily surmounts the common obstacles found in the road is obvious. It is converted into a lever, by means of which the load is lifted with greater case, and its centre of gravity passes over in the direction of an easy arc, the obstacle furnishing the fulcrum, on which the lever acts. From this last remark, it might in truth be inferred that the ease with which wheels surmount stones and similar obstacles, is in proportion to their size. This arises from the well known principle, that the longer the arm of a lever is, on which a given force acts, the greater is the result. It may also be added in favor of large wheels, that they sink less in soft ground than small ones, and are less liable to wear out; since, in passing over a given space, they turn round a proportionably less number of times. A wheel, which is three feet in diameter will turn round twice, while a wheel, which is six feet in diameter turns but once. Hence, the tire of the former must come in contact with the ground twice as often as that of the latter. It may be mentioned as a diminution of the advantages of large wheels, that in order to preserve the requisite strength, they are necessarily cumbersome, and too AIDS TO LOCOMOTION. heavy for use. But could this objection be obviated, a limit must be assigned for the size of carriage wheels, which is, that the axle should not be above the level of the draught, or breast of the horse. Indeed in practice, it is found expedient to place the point of draught somewhat lower than the middle of the horse's breast. According to Dr. Gregory, a power which moves a sliding body along a horizontal plane, acts with the greatest advantage, as far as friction is concerned, when the line of direction makes an angle of about 18 degrees with the plane. M. Deparcieux states from experiments with carriages, that the angle made by the trace with a horizontal line, should be one of 14 or 15 degrees. Broad Wheels. Much has been written on the comparative utility of wheels which have a broad, or a narrow rim. The advocates for the former kind of wheels urge, that they pass more easily over ruts and holes, and sink to a smaller depth in soft and sandy roads. Hence, while narrow rimmed wheels render a road uneven, by causing deep and narrow ruts, the broad constantly act as rollers upon the surface. The principal objections to broad wheels are, their greater weight, greater expense, and the greater number of obstacles, which they meet in their passage. Form of Wheels. Were roads in all cases level and smooth, the proper form of wheels would obviously be an exact cylinder, with their spokes set precisely parallel to the same plane. But experience has proved the advantage of wheels, which are somewhat conical or dishing. In this case, when, by reason of an inequality in the road, the weight of the carriage is chiefly thrown on one wheel, the spokes on the under side of that wheel becoming more nearly vertical, are better able to sustain the increased pressure. A further advantage presented by this form of wheels is, that the circumference being farther from the body of the carriage, less mud is thrown upon it, and the passengers are less annoyed. The chief objection to this form of the wheel is presented in an increase of friction, it being found that the degree of lateral motion and friction increases in proportion, as the wheel is conical or dishing. MODE OF ATTACHING A HORSE. In cities, it is the general custom, growing probably out of the circumscribed limits of wharves, which draymen much frequent, and the narrowness of the alleys, through which they pass, to harness draught horses before each other, in a single line. This is, however, a bad mode of attaching horses, since only the shaft horse has an advantageous line of draft. The other horses draw nearly in a horizontal line, and of course to a disadvantage. Besides, the foremost horses, drawing at the ends of the shaft, do not act directly upon the load, but expend a part of their force in a vertical pressure upon the back of the shaft horse. A better mode of attaching horses, is to make them work abreast-since they are then in the same line of traction, and are equally near to the load. RAIL ROADS. By the term rail road is understood a road formed by laying distinct tracks of timber, iron, or stone, for wheel carriages to run upon. They are of modern invention. The earliest rail roads were constructed of wood only. Stone is sometimes employed, but iron only should be used where durability is expected. |