The Clyde from its source to the sea, its development as a navigable river, the rise and progress of marine engineering and shipbuilding on its banks, and the leading historical, geological, and meteorological features of the Clyde Valley . I Cross Scctiou of Muiiui; iiuik is considerable, in proportion to the steam used. Thus,if the steam were not used expansively at all thepressure would be uniform throughout the stroke; buta whole cylinder full of steam would be used. If cutoff at say half-stroke, the mean pressure would now heapproximately seven-eighths of what it was in thefirst case. But
The Clyde from its source to the sea, its development as a navigable river, the rise and progress of marine engineering and shipbuilding on its banks, and the leading historical, geological, and meteorological features of the Clyde Valley . I Cross Scctiou of Muiiui; iiuik is considerable, in proportion to the steam used. Thus,if the steam were not used expansively at all thepressure would be uniform throughout the stroke; buta whole cylinder full of steam would be used. If cutoff at say half-stroke, the mean pressure would now heapproximately seven-eighths of what it was in thefirst case. But only one-half of the steam is now used. THE RIVER. 227 It is, therefore, economical to use the expansive forceof the steam; and to do this with the greatest effecta long cylinder or a series of cylinders is necessary. It isalso necessary that the initial pressure be high, so as totake advantage of expansion to the fullest. JM::^. Longitudinal Section of Marine Boiler. In the compound system, therefore, an advantageis gained; and in the triple and quadruple systemsa still further improvement arises from the use of steamat a higher pressure and expanded more fully, wherebyless steam can be made to give a better mean saving is thus effected, both in coal consumed andin boiler space. Pressures have now reached 160 lbs. and 228 THE CLYDE: FROM SOURCE TO SEA. 170 lbs. per square inch, and will, no doubt, go higherstill. The limit of economical working cannot, however,be far off, as with increased pressure difficulties will bemet from the greater heat of the steam affecting theworking parts. The whole question of economical working, in a word,depends upon the amount of effective work which canbe obtained from the coal consumed. So that, not onlyis the engine subject to further improvement, but alsothe boiler and furnace. Combustion by forced draught,&c., are all elements in the question. From the combus-
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Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondo, bookyear1888
