Chap. X.

VALUE OF ARTIFICERS’ WORKS.

895

Yarns spun from 20 to 60 leas to the pound require nearly the same preparation andmachinery, and a horse-power is equal to 120 spindles in the wet and warm way.

In Yams spun from 60 to 100 leas to the pound, a horse-power will work 200 spin-dles, including all the preparation ; but the spindles and attendant machinery will be lighterthan in the other cases.

In Cotton Mills the throstle spindle is used for the coarser yarns, and for the finer kindsthe mule spindle.

With Throstle Spindles few manufacturers spin a coarser kind than 10 leas to the pound,none higher than 30; taking 20 as a fair average, the horse-power would drive 180spindles.

With Mule Spindles , at an average of 50 leas to the pound, a horse-power, including thepreparations, will turn 500 spindles, and this is varied up to 1000 spindles to the horse-power ; but in this latter case the cotton must be clean, of superior quality, and spun to thefiner degrees. By inquiries based upon the foregoing, the number of horse-power may beobtained, and consequently the value of the water-power.

Paper Mills , saw mills and others containing machinery driven by water, may be allestimated, and their value determined by calculating in the same manner.

Before the valuator commences any survey, he must be provided with good maps, havinga field scale, and proper measuring rods or tape for taking the dimensions of the buildingsthat are upon the estate.

Where the district is mountainous or hilly, it is also necessary that he should carefullyexamine the crops, and make due allowance for the difference of elevation, and where landlies in the interior of a mountain, or is surrounded by high land, some consideration shouldbe allowed : land also which has a southern aspect is of more value than that which lies tothe north, and Vitruvius explains to us why that species of fir known at Rome by the nameof supernas is not so good as that which is called infernas, whose durability in buildings is sogreat ; “ the hither side of the Apennines towards Tuscany and Campania is in point ofclimate extremely mild, being continually warmed by the sun’s rays ; the further side,which lies towards the upper sea, is exposed to the north, and is inclosed by thick andgloomy shadow. The trees, therefore, which grow at that part being nourished by continualmoisture, not only grow to a great size, but their fibres, being too much saturated with it,swell out considerably, and then are unfit for building : those which grow in sunny placesare more solid, and, in consequence of the closeness of their pores, are exceedingly lasting.The infernas, as those firs are called which are brought from warm open parts, are preferableto the sort called supernas, which come from a closely and thick-wooded country.”

CHAP. X.

VALUE OF ARTIFICERS’ WORKS IN ENGINEERING.

The exact valuation of the price of work being one of the most important elements inthe execution of great enterprises, the basis upon which it should be founded, it is our firstduty to consider.

The price of work depends upon several elements, which may be classed as follows: —

The prime cost of the materials :

The waste which occurs in converting them to use :

The manual labour:

The incidental expences, such as tools, machines, workshops, &c. &c. ; and persons em-ployed as clerks of the works, foreman, &c. :

The interest of money on capital, and the profit thereon.

The principal materials employed are stone, brick, lime, sand, and other substances whichunite with lime; timber, iron, lead, copper, &c.

The price of these comprehend, first, that of the material itself, then its conversion andcarriage. The only method of estimating its value is to acquire a correct knowledgeof these three objects, and particularly the manual labour consumed in its conversion, whichgenerally forms the chief item: usually the price current of the materials is the one actedupon ; and these vary according to circumstances. The loss which materials suffer in theiremployments depends in part upon their quality, and on the workmen, as well as the careand diligence of those who direct them. The manual labour is not so difficult to ascertain.

The execution of work may be divided into three operations,— preparing the materials,their carriage, and fixing; each of these may be subdivided and separately calculated :among the tools employed, some are found by the workmen, and the wear and tear forms aportion of the labour ; some of the machines used in large works are provided by the go-vernment, or the company that promotes them.