III. Economy in the Generation and Transmission of Power, and in Buildings
In his October 1852 report L. Horner quotes a letter of the famous engineer James Nasmyth of Patricroft, the inventor of the steam-hammer, which, among other things, contains the following*:
"... The public are little aware of the vast increase in driving power which has been obtained by such changes of system and improvements" (of steam-engines) "as I allude to. The engine power of this district" (Lancashire) "lay under the incubus of timid and prejudiced traditions for nearly forty years, but now we are happily emancipated. During the last fifteen years, but more especially in the course of the last four years" (since 1848), "some very important changes have taken place in the system of working condensing steam-engines. ... The result ... has been to realise a much greater amount of duty or work performed by the identical engines, and that again at a very considerable reduction of the expenditure of fuel. ... For a great many years after the introduction of steam-power into the mills and manufactories of the above-named districts, the velocity of which it was considered proper to work condensing steam-engines was about 220 feet per minute of the piston; that is to say, an engine with a 5-feet stroke was restricted by 'rule' to make 22 revolutions of the crankshaft per minute. Beyond this speed it was not considered prudent or desirable to work the engine; and as all the mill gearing ... were made suitable to this 220 feet per minute speed of piston, this slow and absurdly restricted velocity ruled the working of such engines for many years. However, at length, either through fortunate ignorance of the 'rule', or by better reasons on the part of some bold innovator, a greater speed was tried, and as the result was highly favourable, others followed the example, by, as it is termed, 'letting the engine away', namely, by so modifying the proportions of the first motion wheels of the mill gearing as to permit the engine to run at 300 feet and upwards per minute, while the mill gearing generally was kept at its former speed.... This 'letting the engine away'... has led to the almost universal 'speeding' of engines, because it was proved that not only was there available power gained from the identical engines, but also as the higher velocity of the engine yielded a greater momentum in the fly-wheel the motion was found to be much more regular.... We ... obtain more power from a steam-engine by simply permitting its piston to move at a higher velocity (pressure of steam and vacuum in the condenser remaining the same).... Thus, for example, suppose any . given engine yields 40 horse-power when its piston is travelling at 200 feet per minute, if by suitable arrangement or modification we can permit this same engine to run at such a speed as that its piston will travel through space at 400 feet per minute (pressure of steam and vacuum, as before said, remaining the same), we shall then have just double the power ... and as the pressure by steam and vacuum is the same in both cases, the strain upon the parts of this engine will be no greater at 400 than at 200 feet speed of piston, so that the risk of 'break-down' does not materially increase with the increase of speed. All the difference is, that we shall in such case consume steam at a rate proportional to the speed of piston, or nearly so; and there will be some small increase in the wear and tear of 'the brasses' or rubbing-parts, but so slight as to be scarcely worth notice.... But in order to obtain increase of power from the same engine by permitting its piston to travel at a higher velocity it is requisite ... to burn more coal per hour under the same boiler, or employ boilers of greater evaporating capabilities, i. e., greater steam-generating powers. This accordingly was done, and boilers of greater steam-generating or water-evaporating powers were supplied to the old 'speeded' engines, and in many cases near 100 per cent more work was got out of the identical engines by means of such changes as above named. About ten years ago the extraordinary economical production of power as realised by the engines employed in the mining operations of Cornwall began to attract attention; and as competition in the spinning trade forced manufacturers to look to 'savings' as the chief source of profits, the remarkable difference in the consumption of coal per horse-power per hour, as indicated by the performance of the Cornish engines, as also the extraordinary economical performance of Woolf s double-cylinder engines, began to attract increased attention to the subject of economy of fuel in this district, and as the Cornish and double-cylinder engines gave a horse-power for every 3 -— to 4 pounds of coal per hour, while the generality of cotton-mill engines were consuming 8 or 12 pounds per horse per hour, so remarkable a difference induced mill-owners and engine-makers in this district to endeavour to realise, by the adoption of similar means, such extraordinary economical results as were proved to be common in Cornwall and France, where the high price of coal had compelled manufacturers to look more sharply to such costly departments of their establishments. The result of this increased attention to economy of fuel has been most important in many respects. In the first place, many boilers, the half of whose surface had been in the good old times of high profits left exposed quite naked to the cold air, began to get covered with thick blankets of felt, and brick and plaster, and other modes and means whereby to prevent the escape ofthat heat from their exposed surface which had cost so much fuel to maintain. Steam-pipes began to be 'protected' in the same manner, and the outside of the cylinder of the engine felted and cased in with wood in like manner. Next came the use of'high steam', namely, instead of having the safety-valve loaded so as to blow ofT at 4, 6, or 8 lbs to the square inch, it was found that by raising the pressure to 14 or 20 lbs ... a very decided economy of fuel resulted; in other words, the work of the mill was performed by a very notable reduced consumption of coals, ... and those who had the means and the boldness carried the increased pressure and 'expansion system' of working to the full extent, by employing properly constructed boilers to supply steam of 30, 40, 50, 60, and 70 lbs to the square inch; pressures which would have frightened an engineer of the old school out of his wits. But as the economic results of so increasing the pressure of steam ... soon appeared in most unmistakable £ s. d. forms, the use of high-pressure steam-boilers for working condensing engines became almost general. And those who desired to go to the full extent ... soon adopted the employment of the Woolf engine in its full integrity, and most of our mills lately built are worked by the Woolf engines, namely, those on which there are two cylinders to each engine, in one of which the high-pressure steam from the boiler exerts or yields power by its excess of pressure over that of the atmosphere, which, instead of the said high-pressure steam being let pass off at the end of each stroke free into the atmosphere, is caused to pass into a low-pressure cylinder of about four times the area of the former, and after due expansion passes to the condenser, the economic result obtained from engines of this class is such that the consumption of fuel is at the rate of from 3— to 4 lbs of coal per horse per hour; while in the engines of the old system the consumption used to be on the average from 12 to 14 lbs per horse per hour. By an ingenious arrangement, the Woolf system of double cylinder or combined low- and high-pressure engine has been introduced extensively to already existing engines, whereby their performance has been increased both as to power and economy of fuel. The same result ... has been in use these eight or ten years, by having a high-pressure engine so connected with a condensing engine as to enable the waste steam of the former to pass on to and work the latter. This system is in many cases very convenient.
"It would not be very easy to get an exact return as to the increase of performance or work done by the identical engines to which some or all of these improvements have been applied; I am confident, however, ... that from the same weight of steam-engine machinery we are now obtaining at least 50 per cent more duty or work performed on the average, and that ... in many cases, the identical steam-engines which, in the days of the restricted speed of 220 feet per minute, yielded 50 horse-power, are now yielding upwards of 100. The very economical results derived from the employment of high-pressure steam in working condensing steam-engines, together with the much higher power required by mill extensions from the same engines, has within the last three years led to the adoption of tubular boilers, yielding a much more economical result than those formerly employed in generating steam for mill engines" (Reports of Insp. of Fact., October 1852, pp. 23-27).
What applies to power generation also applies to power transmission and working machinery.
"The rapid strides with which improvement in machinery has advanced within these few years have enabled manufacturers to increase production without additional moving power. The more economical application of labour has been rendered necessary by the diminished length of the working day, and in most well-regulated mills an intelligent mind is always considering in what manner production can be increased with decreased expenditure. I have before me a statement, kindly prepared by a very intelligent gentleman in my district, showing the number of hands employed, their ages, the machines at work, and the wages paid from 1840 to the present time. In October 1840, his firm employed 600 hands, of whom 200 were under 13 years of age. In October last, 350 hands were employed, of whom 60 only were under 13; the same number of machines, within very few, were at work, and the same sum in wages was paid at both periods" (Redgrave's Report in Reports of Insp. of Fact., Oct. 1852, pp. 58-59).
These improvements of the machinery do not show their full effect until they are used in new, appropriately arranged factories.
"As regards the improvement made in machinery, I may say in the first place that a great advance has been made in the construction of mills adapted to receive improved machinery... In the bottom room I double all my yarn, and upon that single floor I shall put 29,000 doubling spindles. I effect a saving of labour in the room and shed of at least 10%, not so much from any improvement in the principle of doubling yarn, but from a concentration of machinery under a single management; and I am enabled to drive the said number of spindles by one single shaft, a saving in shafting, compared with what other firms have to use to work the same number of spindles, of 60%, in some cases 80%. There is a large saving in oil, and shafting, and in grease.... With superior mill arrangements and improved machinery, at the lowest estimate I have effected a saving in labour of 10%, a great saving in power, coal, oil, tallow, shafting and strapping" (Evidence of a cotton spinner, Reports of Insp. of Fact., Oct. 1863, pp. 109, 110).