cost to him to whom it was so deeply indebted for the extension of its resources and the augmentation of its power, the reply was that such a measure could not be adopted as it might be drawn into a precedent in like cases thereafter ! A precedent in like cases!! When will the time arrive when the world will produce a like case? The monument which has been erected in Westminster Abbey was in fact raised by private subscription, the nation having thus stigmatised itself through the act of its government with the everlasting disgrace of refusing the honour proposed to it. The other statues and monuments which have been erected to this great man, have been for the most part raised by the filial piety and the never-dying affection and veneration of the present Mr. James Watt. A statue has been presented by him to the University of Glasgow, and placed in one of the halls of that college. The inhabitants of Greenock have also erected a marble statue of Watt, for which, and for a library, a building has been erected at the expense of about 3,500l. which has been defrayed by Mr. James Watt. A colossal bronze statue has been erected on a handsome granite pedestal, standing at one of the corners of George Square, Glasgow. The monument in Westminster Abbey, erected by the subscription raised at the public meeting already alluded to, is a colossal statue of Carrara marble, by Chantrey. Watt was elected a fellow of the Royal Society of Edinburgh in 1784; of the Royal Society of London in 1785; a member of the Batavian Society in 1787; and a corresponding member of the Institut of France in 1808. The degree of Doctor of Laws was conferred upon him by the University of Glasgow, in 1806; and in 1814, the highest scientific honour which can be attained by a philosopher, was conferred on him by the Academy of Sciences of the Institut of France, who nominated him one of its eight foreign associates. On the pedestal of the monument in Westminster Abbey is engraved the following inscription from the pen of Lord Brougham: NOT TO PERPETUATE A NAME WHICH MUST ENDURE WHILE THE PEACEFUL ARTS FLOURISH, BUT TO SHOW THAT MANKIND HAVE LEARNED TO HONOUR THOSE THE KING HIS MINISTERS, AND MANY OF THE NOBLES AND COMMONERS OF THE REALM RAISED THIS MONUMENT TO WHO DIRECTING THE FORCE OF AN ORIGINAL GENIUS, TO THE IMPROVEMENT OF THE STEAM ENGINE, ENLARGED THE RESOURCES OF HIS COUNTRY, AND ROSE TO AN EMINENT PLACE AMONG THE MOST ILLUSTRIOUS FOLLOWERS OF SCIENCE AND THE REAL BENEFACTORS OF THE WORLD. BORN AT GREENOCK MDCCXXXVI. DIED AT HEATHFIELD IN STAFFORDSHIRE MDCCCXIX. 1 ENGINE.-TREVETHICK AND VIVIAN. -EFFECTS OF RAILWAY TRANSPORT.-HISTORY OF THE LOCO- (180.) IN the various modifications of the steam engine which we have hitherto considered, the pressure introduced on one side of the piston derives its efficacy either wholly or partially from the vacuum produced by condensation on the other side. This always requires a condensing apparatus, and a constant and abundant supply of cold water. An engine of this kind must therefore necessarily have considerable dimensions and weight, and is inapplicable to uses in which a small and light machine only is admissible. If the condensing apparatus be dispensed with, the piston will always be resisted by a force equal to the atmospheric Y pressure, and the only part of the steam pressure which will be available as a moving power, is that part by which it exceeds the pressure of the atmosphere. Hence, in engines which do not work by condensation, steam of a much higher pressure than that of the atmosphere is indispensably necessary, and such engines are therefore called high-pressure engines. We are not, however, to understand that every engine, in which steam is used of a pressure exceeding that of the atmosphere, is what is meant by an high-pressure engine; for in the ordinary engines in common use, constructed on Watt's principle, the safety-valve is loaded with from 3 to 5 lbs. on the square inch; and in Woolf's engines, the steam is produced under a pressure of 40 lbs. on the square inch. These would therefore be more properly called condensing engines than low-pressure engines; a term quite inapplicable to those of Woolf. In fact, by high-pressure engines is meant engines in which no vacuum is produced, and, therefore, in which the piston works against a pressure equal to that of the atmosphere. In these engines the whole of the condensing apparatus, viz. the cold-water cistern, condenser, air-pump, cold-water pump, &c., are dispensed with, and nothing is retained except the boiler, cylinder, piston, and valves. Consequently, such an engine is small, light, and cheap. It is portable also, and may be moved, if necessary, along with its load, and is therefore well adapted to locomotive purposes. (181.) High-pressure engines were one of the earliest forms of the steam engine. The contrivance, which is obscurely described in the article already quoted (7.), from the Century of Inventions, is a high-pressure engine; for the power there alluded to is the elastic force of steam working against the atmospheric pressure. Newcomen, in 1705, applied the working-beam, cylinder, and piston to the atmospheric engine; and Leupold, about 1720, combined the working-beam and cylinder with the high-pressure principle, and produced the earliest high-pressure engine worked by a cylinder and piston. The following is a description of Leupold's engine: A (fig. 82.) is the boiler, with the furnace beneath it; c c are two cylinders with solid pistons P P', connected with the working-beams B B', to which are attached the pump-rods RR', of two forcing pumps F F', which communicate with a great force-pipe s; & is a four-way cock (66.) already described. In the position in which it stands in the figure, the steam issues from below the piston P into the atmosphere, and the piston is descending by its own weight; steam from the boiler is at the same time pressing up the piston P', with a force equal to the difference between the pressure of the steam and that of the atmosphere. Thus the piston R of the forcing-pump is being drawn up, and the piston p' is forcing the piston R' down, and thereby driving water into the force |