THE DEATH OF DR. BLACK.
In the society of friends such as Adam Smith, Hume, Carlyle, Home, Hutton, Playfair, and Dugald Stewart, the closing days of this great and gentle chemist wore tranquilly away. Towards the end, he sank into a low state of health, and only preserved himself from the severe shocks of the weather in the changeable climate of Edinburgh, by a degree of care and abstemiousness rarely surpassed even by the devoutest Brahmin. "It was his generous and manly wish, that he might never live to be a burden to his friends; and never was the wish more completely gratified. On the 26th November 1799, in the seventy-first year of his age, he expired without any convulsion, shock, or stupor, to announce or retard the approach of death. Being at table with his usual fare—some bread, a few prunes, and a measured quantity of milk diluted with water; and having the cup in his hand when the last stroke of the pulse was to be given, he had set it down upon his knees, which were joined together, and kept it steady with his hand in the manner of a person perfectly at ease; and in this attitude expired, without spilling a drop, and without a writhe in his countenance; as if an experiment had been required, to show to his friends the facility with which he departed. His servant opened the door to tell him that some one had left his name; but getting no answer, stepped about half way towards him, and, seeing him sitting in that easy posture, supporting his basin of milk with one hand, he thought that he had dropped asleep, which he had sometimes seen happen after his meals. The man went back and shut the door; but before he got down stairs, some anxiety that he could not account for made him return, and look again at his master. Even then, he was satisfied, after coming pretty near, and turned to go away; but again returned, and coming quite close, found his master without life."
ORIGIN OF THE TELEGRAPH.
When Arthur Young made his well-known journey in France, in the year 1787 to 1789, he met, he tells us, with a Monsieur Lomond, "a very ingenious and inventing mechanic," who had made a remarkable discovery in electricity. "You write two or three words on a paper," says Young: "he takes it with him into a room, and turns a machine enclosed in a cylindrical case, at the top of which is an electrometer, a small, fine, pith ball; a wire connects with a similar cylinder and electrometer in a distant apartment; and his wife, by remarking the corresponding motions of the ball, writes down the words they indicate; from which it appears that he has formed an alphabet of motions. As the length of the wire makes no difference in the effect, a correspondence might be carried on at any distance. Whatever the use may be, the invention is beautiful." This discovery, however, lay unnoticed until about the year 1845; though the apparatus was designed to effect the same end as the electric telegraph, by means very similar.
The possibility of applying electricity to telegraphic communication was conceived by several other persons, long before it was attempted upon a practical scale. The Rev. Mr. Gamble, in his description of his original shutter-telegraph, published towards the close of the last century, alludes to a project of electrical communication. Mr. Francis Ronalds, in a pamphlet on this subject, published in 1823, states that Cavallo proposed to convey intelligence by passing given numbers of sparks through an insulated wire; and that, in 1816, he himself made experiments upon this principle, which he deemed more promising than the application of galvanic or voltaic electricity, which had been projected by some Germans and Americans. He succeeded perfectly in transmitting signals through a length of eight miles of insulated wire; and he describes minutely the contrivances necessary for adapting the principle to telegraphic communication.
It is, however, to the combined labours of Mr. W. F. Cooke and Professor Wheatstone that electric telegraphs owe their practical application; and, in a statement of the facts respecting their relative positions in connection with the invention, drawn up at their request by Sir M. I. Brunel and Professor Daniell, it is observed that "Mr. Cooke is entitled to stand alone, as the gentleman to whom this country is indebted for having practically introduced and carried out the electric telegraph as a useful undertaking, promising to be a work of national importance; and Professor Wheatstone is acknowledged as the scientific man whose profound and successful researches had already prepared the public to receive it as a project capable of practical application."—Penny Cyclopædia.
NECESSITY THE MOTHER OF INVENTION.
When Vitiges, king of the Goths, besieged Belisarius in Rome in 536, and caused the fourteen large aqueducts to be stopped, the city was subjected to great distress, not on account of the want of water in general, for it was secured against that inconvenience by the Tiber, but on account of the loss of that water which the baths required, and, above all, of that necessary to drive the mills, which were all situated on these canals. Horses and cattle, which might have been employed in grinding, were not to be found; but Belisarius, a man of great ingenuity, devised an expedient to remedy this distress. Below the bridge that reached to the wall of Janiculum, he extended ropes, well fastened, and stretched across the river from both banks. To these he affixed two boats of equal size, at the distance of two feet from each other, where the current flowed with the greatest rapidity, under the arch of the bridge; and, placing large millstones on one of the boats, suspended in the middle space a machine by which they were turned. He constructed at certain intervals on the river other machines of the same description, which, being put in motion by the force of the water that ran below them, drove as many mills as were necessary to grind provisions for the city. To destroy these, the besiegers threw into the stream logs of wood, and dead bodies, which floated down the river into the city; but the besieged, by making use of booms to stop them, were enabled to drag them out before they did any mischief. This is said to have been the first invention of floating mills.