Pre

of the Works to Charles II., and in the following year was sent to France, to execute some waterworks for Louis XIV. In 1683, while in France, he wrote in the French language, a work entitled “ Elevation des Eaux par toute sorte de Machines, reduite à la Mesure, au Poids et à la Balance. sentée à sa Majesté très Chrestienne, par le Chevalier Morland, Gentilhomme Ordinaire de la Chambre Privée, et Maistre des Méchaniques du Roi de la Grande Brétagne, 1683." This book is preserved in manuscript in the Harleian Collection in the British Museum. It is written on vellum, and consists of only thirty-eight pages. It contains tables of measures and weights, theorems for the calculation of the volumes of cylinders, the weights of columns of water, the thickness of lead for pipes, and is concluded by a chapter on steam, consisting of four pages, of which the following is a translation:

"The principles of the new force of fire invented by Chevalier Morland in 1682, and presented to his Most Christian Majesty in 1683:

"Water being converted into vapour by the force of fire, these vapours shortly require a greater space (about 2000 times) than the water before occupied, and sooner than be constantly confined would split a piece of cannon. But being duly regulated according to the rules of statics, and by science reduced to measure, weight, and balance, then they bear their load peaceably (like good horses), and thus become of great use to mankind, particularly for raising water, according to the following table, which shows the number of pounds that may be raised 1800 times per hour to a height of six inches by cylinders half filled with water, as well as the different diameters and depths of the said cylinders.""

There is nothing in the description here given which can indicate the form of the machine by which Morland proposed to render the force of steam a useful mover. It is, however, remarkable, that at this early period, before experiments had been made on the expansion which water undergoes in evaporation, he should have given so near an approximation to

the actual amount of that expansion. It is scarcly supposable that such an estimate could be obtained by him otherwise than by experiment.

The work containing the above description was not printed; but a work bearing nearly the same title, containing, however, no mention of the force of steam, was published by him in Paris in the year 1685. In this he describes various experiments made by him at St. Germains on the weight of the water of the Seine, and gives weights of the columns of water, the contents of cylinders, &c.

Soon after the publication of this work, Morland returned to England, and resided near the court till his death. The celebrated John Evelyn mentioned having paid a visit to him at his house at Hammersmith, in 1695, when he had become aged and blind, but was still remarkable for his mechanical ingenuity. "On the 25th of October," says Evelyn, "the Archbishop and myself went to Hammersmith to visit Sir Samuel Morland, who was entirely blind; a very mortifying sight. He showed us his invention of writing (short-hand), which was very ingenious; also his wooden kalendar, which instructed him all by feeling; and other pretty and useful inventions of mills, pumps, &c.; and the pump he had erected, that serves water to his garden and to passengers, with an inscription, and brings from a filthy part of the Thames near it a most perfect and pure water."

He died at Hammersmith, in January 1696; and before his death, as a penance for his past life, was guilty of the eccentricity of burying in the ground six feet deep a great collection of music which he possessed.†

DENIS PAPIN, 1688.

(19.) Denis Papin, a native of Blois in France, and professor of mathematics at Marbourg, is the name which stands next recorded in the progressive invention of the steam engine. To this philosopher is due the discovery of one of the qualities of steam, to the proper management of which is owing much of the efficacy of the modern steam engine.

* Farey, Treatise on the Steam Engine, p. 93.

Arago, sur les Machines à Vapeur, Annuaire, 1829, p. 165.

Papin was born at Blois in France. He devoted his youth to the study of medicine, in which he took a degree at Paris. The revocation of the Edict of Nantes having driven him into exile, he went to England, where the celebrated Boyle associated him in several of his experiments with the air-pump, and caused him to be elected a fellow of the Royal Society in 1681. Having been invited to Germany by the Landgrave of Hesse, he discharged during several years the duties of professor of mathematics at the university of Marbourg, where he died in 1710. Notwithstanding his discoveries respecting the agency of steam, he never received any mark of distinction in his own country. The truth is, the importance and value of these investigations were not apparent until long afterwards.

This philosopher conceived the idea of producing a moving power by means of a piston working in a cylinder, in the manner which we shall now briefly explain.

Let A B (fig. 7.) be a cylinder open at the top, and let a piston p be fitted into it, so as to move in it air tight. At the bottom of the cylinder suppose an opening provided, which can be closed at pleasure, by a stop-cock, or otherwise, so that the communication may be opened and closed at will between the interior of the cylinder and the external air. This stop-cock being opened, let the piston be drawn upwards till it reach the top of the cylinder. Let the stop-cock at the bottom be then removed, and imagine that some means Fig. 7.

can be supplied by which the air within the cylinder can be suddenly annihilated. The piston, now at the top, will have above it the pressure of the atmosphere; and having no air below, it will be resisted in its descent by no force save that arising from its friction with the cylinder. If, then, the force of the air above the piston be greater than the resistance arising from this friction, the piston will descend with the excess of this force, and will continue so to descend until it reach the bottom of the cylinder. Having attained that position, let us

B

C

suppose the stop-cock in the bottom opened, so as to allow the external air to pass freely below the piston. The piston may now be drawn to the top of the cylinder again, offering no resistance save that of its weight, and its friction with the cylinder. Having reached the top of the cylinder once more, let the stop-cock be closed, and the air included within the cylinder once more annihilated. A second descent of the piston will take place, with the same force as before, and in like manner the process may be continued indefinitely.

Now, if it should appear that means could be provided suddenly and repeatedly to annihilate the air within the cylinder, and that the pressure of the atmosphere above the piston should exert a force compared with which the weight of the piston and its friction are trifling, it is evident that a moving power would be obtained which would be capable, by proper. mechanism, of being applied to any useful purpose, but which would more especially be applicable to the working of pumps, the motion of which corresponds with that which has been just ascribed to the piston in the cylinder. Such were the first ideas of Papin. But in order to enable those who are not conversant with physical science fully to appreciate their importance, it will be necessary here to explain some of the mechanical properties of atmospheric air.

(20.) The atmosphere is the thin, transparent, colourless, and therefore invisible, fluid in which we live and move, which by respiration sustains animal life, and is otherwise connected with various important functions of organised matter. This fluid is so light and attenuated, that it might at first be doubted whether it be really a body at all; and, indeed, the name expressing incorporeal beings, spirit, is a word in its origin signifying air. The air, however, is light only as compared with other material substances, which exist in a more condensed state: it possesses the quality of weight as absolutely as the most solid and massive bodies in nature, and to render this quality manifest, it is only necessary to submit a sufficient quantity of air to any of the usual tests of gravitation.

* SPIRITUS, breath or air.

A direct demonstration of this may be given by the following experiment: - On the mouth of a flask let a stopcock be fastened so as to be air-tight. The interior of the flask may then be put into free communication with the external air or that communication may be cut off at pleasure, by opening or closing the stop-cock. If a syringe be applied to the mouth of the flask, the stop-cock being open, a part of the air contained in it may be drawn out. After this, the stop-cock being closed, and the syringe detached, let the flask be placed in the dish of a good balance, and accurately counterpoised by weights in the other dish. This counterpoise will then represent the weight of the flask, and of the air which has remained in it. If the stop-cock be now opened, air will immediately rush in, and replace that which the syringe had withdrawn from the flask; and immediately the dish of the balance containing the flask will sink by the effect of the weight of the air thus admitted into the flask.

If the weight of quantity of air so small as to be capable of being withdrawn by a syringe from an ordinary flask be thus of sensible amount, it may be easily imagined that the vast mass of atmosphere extending from the surface of the earth upwards, to a height not ascertained with precision, but certainly not being less than thirty miles, must be very considerable. Such a force, pressing as it must constantly do, upon the surfaces of all bodies, whether solid or fluid, and resisting and modifying their movements, would play an important part in all mechanical phenomena; and it is, therefore, not sufficient merely to have recognised its existence, but it is most needful to measure its amount with that degree of certainty and precision, which will enable us to estimate its effects on those phenomena which we shall have to investigate.

(21.) The amount of the pressure of the atmosphere on each square inch of horizontal surface on which it rests, is obviously the weight of the column of air extending from that square inch of surface upwards to the top of the atmosphere, This force is measured by the following means :

Take a glass tube, a B (fig. 8.), above 32 inches long, open at one end A, and closed at the other end B, and let it