As horses are the power most commonly applied to overcome agricultural difficulties, it is necessary the mechanical formation of these noble animals should first be considered. A horse's limbs are a system of powerful levers, actuated by muscles of proportionate strength and wonderful contrivance! By these he can carry near 800lb. on his back, draw upwards of 80lb. for hours together, and some of his species have run near a mile in a minute! For beauty, he may be considered as the paragon of animals; and for spirit and courage, incapable of fear, or giving up what he contends for.

The slope of his shoulder, making an angle with a perpendicular to the horizon of about 14 or 15 degrees, shews that the horse was not designed to draw horizontally, or as horses do in a team; for, though it is unnoticed, his collar is drawn up against his throat, and obstructs his breathing: if his collar lie inclined on his shoulder, his line of draught should be perpendicular to it, and consequently incline to the horizon in the aforesaid angle, thus:

D

15°

a is the centre of gravity of the horse; from a to c is the acting part of the lever; from c to b the resisting part; therefore, in thrusting out his hind legs he lengthens a c, and diminishes c b. The muscles of his hind legs add to the power of his weight; but his fore legs are of little use to his draught; they prop the forepart of his body, and by their action lift up his centre of gravity, so that by its fall its weight may act upon obstacles and resistance; for in all difficult draughts a horse has an undulatory motion, rising and falling every step; and it is by the falling part of it, that he overcomes the obstructions to his draught: hence the use of heavy horses for loads. great

If the horizontal line a have the inclined line of draught drawn from the horse's shoulder at an angle of 14° or -15°, it would extend to the bottom of the wheel, as the dotted line c does. This is certainly too low for a line of draught. Therefore, in carts, if the slope be not more than 8 or 10 it will be found more convénient, though less me chanically powerful. This manner of draught, from five or six inches below the axle, has been practised repeatedly with

success.

I therefore apprehend that a four-wheel carriage drawn by the shaft horses at an angle of 10, 12, or 14° (according to the size of the horses) are the best angles, both animal and mechanical, that a horse can draw in.-But as horses in a team must draw horizontally, the shaft horses will have a portion of the weight drawn down on their backs by the pull of the fore-horses; because all lines of draught, if crooked or angular, have a tendency to draw into a straight line.

Where another horse precedes that attached to the body drawn, we have to

guard against the effect of this tendency; for if the line of draught of the nearest horse be adjusted with the nicest accuracy, yet the distance of the one in advance, vacates every reference to the principle of gravity, as attached to him, and ren

ders a different line of draught indispensable. As this is of the greatest consequence to many persons whose vehicles are drawn in this manner, we have copied the figure by which the nature of this action is shewn.

LEVE

Fere Horses

This figure also shews the relative proportions of the height of the wheels. to each other, and to the horse by which they are drawn. But it is evident, that many considerations may render variations desirable; such as, the conveniency of employing horses of different sizes, occasionally the necessity for adopting the forms and constructions of carriages to narrow and crowded streets, to different motions and attitudes, as turning, backing, &c. and to other conveniencies. Mr. W. thinks that the wheels of carriages having but one pair should be about 5 feet 4 inches in height: then forming the line of draught to 12° or 14° (agreeable to the shoulder of the horse), it will follow that the fore wheels of carriages having two pairs, must be much smaller, and this, which he observes is quite necessary for easy turning, may be done without much harm to the draught.

The machines that are usually drawn by horses may be classed under three kinds: coaches, carts, and waggons. The first are fitted for speedy conveyance, and are supposed to be laden rather with passengers than luggage: the second are laden with luggage in small quantities: and the last are understood to be heavily laden with goods of a ponderous kind. The principles on which these machines are constructed are of great consequence, in this inquiry; but, we shall place first the principle on which they are, or ought to be, laden, as being most ordinarily too little attended to in practice.

OF WEIGHT OR GRAVITY.

Weight, or gravity, is the tendency of any body to fall in a direct line, as the nearest way, to the centre of the earth.

laden with corn, one on level ground, the Let these two figures represent two carts other on a declivity; a. the centre of gravity, and a. b. the line in which the loads would fall. In one, there is no danger, because the line of direction falls within the supports : the other must overset, because its directions fall beyond the supports.

In loading waggons, it is necessary that the centre of gravity of the load should be nearer the hind, than the fore, wheels. In carts, the centre of gravity of the load should not be directly over the wheels, but a little in clining towards the horse; as his powers, or momentum, will be increased by a portion of the weight on his back.

It is a law of nature that the centre of gravity endeavours to get as low as it can, and always beneath or behind the power by a chair by any part on my finger, its centre of which it is dragged or suspended. If I hang gravity will always settle under ny finger. If a harrow be yoked to a horse by any part, its centre of gravity will get behind that part when the harrow is put in motion. Hence the absurdity of out-riggers; of horses drawing on one side of the line of direction, wasting their strength and wearing the car

As horses are the power most commonly applied to overcome agricultural difficulties, it is necessary the mechanical formation of these noble animals should first be considered. A horse's limbs are a system of powerful levers, actuated by muscles of proportionate strength and wonderful contrivance! By these he can carry near 800lb. on his back, draw upwards of 80lb. for hours together, and some of his species have run near a mile in a minute! For beauty, he may be considered as the paragon of animals; and for spirit and courage, incapable of fear, or giving up what he contends for.

The slope of his shoulder, making an angle with a perpendicular to the horizon of about 14 or 15 degrees, shews that the horse was not designed to draw horizontally, or as horses do in a team; for, though it is unnoticed, his collar is drawn up against his throat, and obstracts his breathing: if his collar lie inclined on his shoulder, his line of draught should be perpendicular to it, and consequently incline to the horizon in the aforesaid angle, thus:

a is the centre of gravity of the horse; from a to c is the acting part of the lever; from c to b the resisting part; therefore, in thrusting out his hind legs he lengthens a c, and diminishes c b. The muscles of his hind legs add to the power of his weight; but his fore legs are of little use to his draught; they prop the forepart of his body, and by their action lift up his centre of gravity, so that by its fall its weight may act upon obstacles and resistance; for in all difficult draughts a horse has an undulatory motion, rising and falling every step; and it is by the falling part of it, that he overcomes the obstructions to his draught: hence the use of heavy horses for great loads.

If the horizontal line a have the inclined line of draught drawn from the horse's shoulder at an angle of 14° or -15°, it would extend to the bottom of the wheel, as the dotted line c does. This is certainly too low for a line of draught. Therefore, in carts, if the slope be not more than 8 or 10 it will be found more convenient, though less me chanically powerful. This manner of draught, from five or six inches below the axle, has been practised repeatedly with

success.

I therefore apprehend that a four-wheel carriage drawn by the shaft horses at an angle of 10, 12, or 140 (according to the size of the horses) are the best angles, both animal and mechanical, that a horse can draw in.-But as horses in a team must draw horizontally, the shaft horses will have a portion of the weight drawn down on their backs by the pull of the fore-horses; because all lines of draught, if crooked or angular, have a tendency to draw into a straight line.

Where another horse precedes that attached to the body drawn, we have to

guard against the effect of this tendency; for if the line of draught of the nearest horse be adjusted with the nicest accuracy, yet the distance of the one in advance, vacates every reference to the principle. of gravity, as attached to him, and ren

ders a different line of draught indispensable. As this is of the greatest consequence to many persons whose vehicles are drawn in this manner, we have copied the figure by which the nature of this action is shewn.

Fore Horses

This figure also shews the relative proportions of the height of the wheels to each other, and to the horse by which they are drawn. But it is evident, that many considerations may render variations desirable; such as, the conveniency of employing horses of different sizes, occasionally the necessity for adopting the forms and constructions of carriages to narrow and crowded streets, to different motions and attitudes, as turning, backing, &c. and to other conveniencies. Mr. W. thinks that the wheels of carriages having but one pair should be about 5 feet 4 inches in height: then forming the line of draught to 12° or 14° (agreeable to the shoulder of the horse), it will follow that the fore wheels of carriages having two pairs, must be much smaller, and this, which he observes is quite necessary for easy turning, may be done without much harm to the draught.

The machines that are usually drawn by horses may be classed under three kinds: coaches, carts, and waggons. The first are fitted for speedy conveyance, and are supposed to be laden rather with passengers than luggage: the second are laden with luggage in small quantities: and the last are understood to be heavily laden with goods of a ponderous kind. The principles on which these machines are constructed are of great consequence, in this inquiry; but, we shall place first the principle on which they are, or ought to be, laden, as being most ordinarily too little attended to in practice.

OF WEIGHT OR GRAVITY.

Weight, or gravity, is the tendency of any body to fall in a direct line, as the nearest way, to the centre of the earth.

Let these two figures represent two carts laden with corn, one on level ground, the other on a declivity; a. the centre of gravity, and a. b. the line in which the loads would fall. In one, there is no danger, because the line of direction falls within the supports : the other must overset, because its directions fall beyond the supports.

In loading waggons, it is necessary that the centre of gravity of the load should be nearer the hind, than the fore, wheels. In carts, the centre of gravity of the load should not be directly over the wheels, but a little in clining towards the horse; as his powers, or momentum, will be increased by a portion of the weight on his back.

It is a law of nature that the centre of gravity endeavours to get as low as it can, and always beneath or behind the power by which it is dragged or suspended. If I hang a chair by any part on my finger, its centre of gravity will always settle under my finger. If a harrow be yoked to a horse by any part, its centre of gravity will get behind that part when the harrow is put in motion. Hence the absurdity of out-riggers; of horses drawing on one side of the line of direction, wasting their strength and wearing the car

riage; drawing in a small circle, as in threshing machines, &c.

The absurdity of placing any undue portion of weight at any extreme on either side of the direct line of draught, is shewn to ocular demonstration in these figures: it is evident too, that elevating any undue portion of weight above the direct line of draught is not without danger: these two absurdities united, render accidents, when they happen, so fatal, as to cost the lives and injure the limbs, of many hundreds of persons every year. The fact is, that the nearer both weight and draught are kept to a true and direct line, acting most immediately on the centre of gravity, the less danger and the less toil is incurred.

But, weights of all kinds are not felt alike by the power that draws them: there is in live weight a lightness if compared with dead weight: and by mechanical inventions, the comparative gravity of dead weight, also, is considerably diminished.

SPRINGS.

Springs were, in all likelihood, first applied to carriages, with no other view than the accommodation of travellers; they have since been found to answer several important ends. They convert all percussions into mere increase of pressure; thus preserving both the carriage and the materials of the road from the effects of blows; and small obstacles are surmounted, when springs allow the frame and wheels freely to ascend, without sensibly moving the body of the carriage from its place.

Springs, as they regard the ease of draft, in some cases lessen the resistance to the horses in a higher proportion than ten to one. Now, although springs, such as those applied to coaches, cannot be usefully employed for heavy waggons, yet the timber of a waggon may be so adjusted as to yield to sudden shocks on rough roads or pavement.

Indeed, whoever considers the subject even in a popular manner, must perceive, that the springs ease the horses as well as the rider; for, whatever jolting motion the latter receives, is communicated by the rising or falling of the carriage going over obstacles; the force of the horses alone produces this motion, and whatever lessens it lightens the horse's labour.

If sixteen people outside and inside of a stage coach are jolted upward even one-third of an inch in travelling one yard, it will require a constant force of twenty pounds to communicate so much motion to the carriage. The whole friction of the axle-trees does not obstruct the motion of the carriage much nore than this slight vibration.

Now the springs commonly used diminish the resistance occasioned by such jolts above half, so that they are as advantageous as any contrivance that would lessen the friction of the boxes upon the axle-tree in proportion of

two to one.

re-action, in preserving the momentum, or Springs are extremely serviceable by their vis inertia of a carriage.

If a loaded carriage without springs sinks into a hole, the momentum it possessed, is received by the road, and destroyed; and the moving power must overcome the increased resistance. If the load is upon springs, they receive the impulse, and restore it with little injured. Since the receptacles for luggage in diminution; they also prevent the load being stage coaches have been joined to the body, and the whole placed upon springs, the luggage has suffered little injury compared to what it used to do. The proprietors of the Shrewshury coach have paid, in the course of a twelvemonth, before the improvement took place, £600 for goodis damaged in the carriage. Springs, similar to those placed upon the fire engine carriages, would be equal to the load of a waggon, without increasing the height.

LIVE WEIGHT.

With regard to stage coaches, there are two circumstances which require particular consideration, the height of the coach, and the manner in which the load should be disposed. Unfortunately these are left to the decision of the proprietor, or driver, or porter, none of whom are competent to the task, and they are obstinately bent, on preferring strait perches, and an elevated body, without any thing conclusive in practice or experiment to warrant such a preference; that either can affect the draught of the carriage or cattle, is too absurd to demand refutation.

As to the loading, it is nothing but daring ignorance, in support of pecuniary advantage, that bears these men through their determi nation, in carrying such weights on the tops of coaches, as are every day seen going out of town, and coming in.

But the evil of outside passengers and packages, attaches more to the double coaches, than the single-bodied ones, for whereas the single coaches carry six outside passengers, the double ones will carry ten; and whereas the single coaches can carry but a short range of packages, the double one will carry a much longer range, and hence make a double disadvantage as to oversetting; for both the double and single coaches are precisely the same as to the lateral distance of the wheels.

There is another circumstance which attaches great casualty to the safety of passengers, and that is the absolute uncertainty as to the number of inside passengers, by which the centre of gravity is very variable;