Part 160

Carry on trenching and leaf-gathering, and roll lawns and paths. The draining of lawns and flower-beds can now be executed. Let spring flowering plants have the same attention as in January, and bedding plants the same as in November. Do not omit to help the branches of delicate trees to withstand the effects of snow and wind by tying them up with rope yarn (tarred twine).

SUPPLEMENTARY LITERATURE.

Robert Thompson: ‘The Gardener’s Assistant; Practical and Scientific.’ London. Latest edition. 35_s._

See also p. 1012.

_DOMESTIC MOTORS._

It is an acknowledged fact that when an establishment has developed sufficiently to necessitate the employment of a considerable amount of manual labour to meet its various requirements, it is more economical and satisfactory in results to introduce mechanical labour in one or more of its many forms; this especially applies to country residences, where wood cutting, chaff and root cutting, pumping, &c., has to be done, and the machines of the dairy, laundry, &c., need propelling, and the same engine can be also utilised for electric lighting, as the light is only needed when the other machines are at rest. The superiority of mechanical over manual labour is obvious and the economy is now fully acknowledged. An engine has the advantage of executing the work with perfect regularity, the last hour’s work being executed as well and as rapidly as the first, and it works all day, and every day and, if desired, all night; and the one motor, if of sufficient power, is capable of being adapted to so many different purposes, together or independently.

_Wind._--Wind engines or mills have the decided advantage of being very economical, but are necessarily irregular in action and are only suited for high or open situations. They are rarely of practical use in towns, or where buildings, trees, &c., exist in any size or number, but where the situation is favourable they are to be highly commended for several purposes, pumping especially. They invariably take the form of a strong vertical structure or framework, surmounted with the mechanism to which the sails are attached, and from which is carried a shaft to the base (somewhat similar to Miller’s wind mills). Warner & Co., of Cripplegate, London, make a specialty of these motors, adapted for numberless purposes, and in which high powers are attainable. Fig. 181 shows an annular sailed wind engine, as applied for pumping; it will be understood that the engine can be stood immediately over the well, or it can be fixed in some more convenient and suitable position and connected with the well by shaft or by pipe.

The illustration will acquaint the reader with details more fully, and it will be noticed that these engines are self-regulating, i.e. means are provided to shift the position of the sail automatically as the wind varies; in the larger sizes “striking” gear is fitted for setting the blades of the sail out of the wind when needed. The illustration represents a No. 2 Warner’s wind engine, with 10 ft. sail, price 25_l._, including pump and timber supports; this size is capable of raising 240 gal. of water per hour 50 ft. high, but the sizes may be smaller or larger as the requirements demand; after the first cost the expense is comparatively ended, as only lubrication is needed.

_Water._--Water wheels also have the advantage of being economical, and greater reliance can be placed on the regularity of water than in wind power; but it is only for those that have rivers, streams, &c., at disposal. Those that are favourably situated cannot too highly prize the power they possess, as very regular and very high powers can be obtained _at will_ and at a moment’s notice, free of cost (excepting first outlay), and requiring scarcely any attention.

Water wheels are of three kinds, viz. overshot, breast, and undershot; as the names signify, the water flows over, or to the breast, or under the wheel, the difference in construction consisting in the shape of the blades on the wheel’s circumference. The first of the three is undoubtedly the most powerful, as not only is the impulse of the flowing water imparted to the blades, but the blades themselves are so constructed that they retain a portion of the water for about a third of a revolution and thus very materially assist by gravitation; the breast wheel is driven by the weight of the water retained by the blades only, and the undershot wheel is driven by the impulse of the water flowing beneath.

Warner & Co., of Cripplegate, London, make a specialty of these machines. Fig. 182 shows an overshot wheel adapted for pumping pure water from a well, and delivering it at any high elevation while being worked by a stream of impure water.

There is practically no limit to the size and power of these wheels, a 50 ft. wheel giving as high as 54 horse-power. The illustration is a No. 1 Warner’s galvanised iron overshot wheel, price 25_l._, including framework and double action pump, with air vessel complete, capable of lifting ½ gal. of water per minute 60 ft. high through 400 ft. of delivery pipe. The power of these wheels is not only increased as the diameter increases, but also by increasing the width of the blades; for instance, a Warner’s wrought iron overshot or high breast wheel of 20 ft. diameter with blades 3 ft. wide, develops 11 horse-power, and the same diameter with 6 ft. blades very naturally gives double (22 horse-power), but with only about 30 per cent. increased cost.

_Turbines_ are a form of water motor which require a head of water, i.e. the water for propelling them must be supplied by means of pipes from a height; for a moderate power, with the majority of turbines, it should be not less than 12 ft.; the higher the head of water the greater the pressure, and the smaller the turbine requires to be for a given amount of work or power (this applies to all water motors), consequently the cost of the motor is less, the pipes smaller, and there is decided economy in the quantity of water used as the height increases. The pressure of water in pipes is 1 lb. to the square inch for every 2 ft. 4 in. in height (not allowing for friction); thus it will be seen that the surface in a turbine upon which the pressure of water is exerted, requires to be double the area with a 20 ft. fall than with a 40 ft. fall for given power. A Warner’s 5 horse-power turbine for 16 ft. fall uses 220 ft. of water per minute with a wheel of 13 in. diameter, giving 377 revolutions a minute, and costing 60_l._, whereas a 5 horse-power turbine for 30 ft. fall uses 118 ft. of water with an 8 in. wheel giving 853 revolutions a minute and costs 45_l._ Fig. 183 shows a Warner’s (Redtenbacher Jouval) improved turbine fitted and connected to a driving shaft. This turbine is made to work with as low a fall as 2 ft., giving 1 horse-power, but the cost is necessarily high. It will be seen from the illustration (which is in section), that the water is made to pass between fixed oblique blades or palettes, and strikes on the oblique blades of the wheel beneath, these latter blades being at an opposite angle to the fixed blades above; thus a pressure, varying with the height of head of water, is directly exerted on every square inch of the blades of the wheel and great power is obtained.

_Hydraulic Rams_ are self-acting water motors, for the supply of water to great heights and distances; they require a fall of water of 12 in. upwards, and are made to supply either the water that works them, or to supply well water while being worked by a stream of impure water; one of the best makers and authorities upon these motors is John Blake, of Oxford Street Works, Accrington, Lancashire. Fig. 184 shows a Blake’s ram of ordinary construction, for raising a portion of the water that works it; a No. 2 (smallest size), price 12_l._, will raise 300 gal. per day, to say 800 ft. high; a No. 16 will raise 100,000 gal. per day. Fig. 185 shows a ram raising water to a reservoir for general purposes.

A hydraulic ram is undoubtedly the most economical means of raising a supply of water, either for a single residence or for a small town, as they work day and night without attention (or intermittently if desired), and work as well submerged as above water; but they, of course, depend entirely upon a fall of water being obtainable, and this fall or supply must be constant.

_Hydraulic Engines_ are made in various forms, being commonly worked in a similar manner to a steam engine, water under pressure acting upon the piston in place of steam. Fig. 186 represents a “Haag’s” patent water motor adapted for a chaff-cutting machine; Fig. 187 a series of “Thirlmere” water motors, showing the capacities; Fig. 188 a Bailey’s patent hydraulic blower, for chamber or church organs, smiths’ bellows, &c. All these motors are manufactured by W. H. Bailey & Co., of Albion Works, Salford, Manchester, and being small and inexpensive, they are very suitable and convenient for working sewing machines, knife cleaners, washers and manglers, and any domestic machine that entails considerable labour. The power of these motors varies with the pressure of water, if connected with the town’s main (by arrangement with the water company), a very high pressure is generally obtained.

A “Haag’s” motor, No. 2 (smallest size), gives from ¼ to ½ horse-power, 220 revolutions (of the flywheel) a minute, and costs 10_l._ A “Thirlmere” motor, No. 00 (smallest size) gives from 1/70th to 1/30th of a horse-power, and costs 2_l._ 2_s._ A Bailey’s blower No. 1 (smallest size), at 50 lb. pressure, gives a boy power with a 10 in. stroke, and costs 6_l._ 6_s._, and is suitable for a chamber organ; these latter are made to work either vertically or horizontally.

Fig. 189 is a “Ramsbottom” 3 cylinder hydraulic engine (Jno. Ramsbottom, Saynor Road, Hunslet, _Leeds_). This is considered one of the most efficient hydraulic motors yet made, and it possesses an advantage in having no dead points (see Flywheel of Steam Engine), and its action is exceedingly steady and uniform. The illustration will acquaint the reader with its constructive details, which are simple and few in number.

No correct idea can be given as to the cost of working these motors, for as before explained, it depends entirely upon the pressure of water obtainable.

_Steam._--Steam engines are made in very many forms, and it would be impossible for us to describe even a small proportion of those made; for small purposes they are most generally made having engine and boiler combined, but where moderately high powers are needed, and space has to be considered, it is found more economical and convenient to keep them separate; the supply of steam from boiler to engine being conveyed by a pipe. It might be here mentioned that it is necessary that all steam chambers and pipes be coated or covered with some non-conducting material, to prevent loss of heat and consequent condensation of steam, and it is found advantageous to keep the steam at as high a temperature as possible, to increase its efficiency; with most large engines the steam is superheated (i.e. heated to higher than its ordinary temperature) as it passes from boiler to engine.

It is not our intention, neither would it be possible in our limited space, to give a practical treatise upon the steam engine, but it will doubtless be interesting and instructive to many if a general description of the chief features be given. They practically consist of the “boiler,” to which is attached the “feed pump,” “water gauge,” “steam gauge,” and “safety valve.” The “engine,” which consists of the cylinder and piston, “governor,” “cranks,” “eccentrics,” and flywheel.

Boilers take many forms, but in actual principle consist of two sorts, both being cylindrical, one being clear inside, and the other nearly filled with flue tubes, which very greatly increase the heating surface. The first mentioned, which is generally used for large works, and is known as a Cornish boiler, Fig. 190, has a cylindrical outer shell, within which is a smaller cylinder, the space between the two, which is closed at both ends, containing the water as shown. This boiler is fixed in brick-work, and the furnace is situated within the inner cylinder. To increase the power of these boilers, large water tubes are carried across the inside of the inner cylinder (opening into the water chamber at each end) where the flame and heat pass after leaving the furnace.

_Multitubular Boilers_ are generally those that are attached to or combined with the engine, where space is a primary object (locomotive engines have multitubular boilers). Fig. 191 shows the arrangement of this boiler in a vertical position with horizontal tubes (shown without the engine); they are also very commonly made with vertical tubes. All boilers are, or should be, provided with ample accommodation for removing the incrustated deposit, which forms with moderate rapidity, as the water is continually boiling, and as evaporation in a steam boiler is very rapid, the supply of water is constantly being renewed, and each successive charge of water brings its proportion of lime to be deposited. (For fuller details upon incrustation and causes, see Bathroom.)

_The Feed Pump_ is a small pump of ordinary shape and construction, situated near and worked by the engine, its purpose being to supply water to the boiler when needed. Mechanism is provided for throwing it in and out of gear as the water gauge indicates; it will be readily understood that no means can be provided for filling a steam boiler by hand, that is to say, it must be done mechanically, as no loose cover can be provided.

_The Water Gauge_ (Fig. 192) consists of two suitably constructed cocks, both being screwed into the boiler one above and one below the correct or average water level, a strong glass tube extending between them as shown; the water level is necessarily the same in the glass tube as in the boiler and consequently the attendant can see at a glance when water is needed; the object of having cocks at each end of the tube is to prevent the escape of water and steam by closing the cocks should the tube be broken.

_The Steam or Pressure Gauge_ (Fig. 193) is a circular brass case with a dial in front, somewhat similar to a clock; within the case is a small curved tube made so as to be somewhat elastic, this tube is in direct communication with the steam in the boiler. A somewhat peculiar action is relied upon, which is, that as the pressure of steam is exerted within this curved tube, it tends to straighten it, and this, by a simple arrangement of wheels, causes the pointer to move round the dial, which is provided with figures round its edge showing the pressure in pounds (to the square inch) that is exerted in the boiler as the indicator points to them.

The utility of the safety valve (Fig. 194) is obvious. They are invariably made so that by means of a weight or other device they can be regulated to blow off at whatever pressure the engineer dictates, the pressure being indicated by the pressure gauge.

Fig. 195 represents a cylinder with piston inside; the cylinder should be encased with wood or some non-conducting material, or be provided with an outer iron casing or “jacket,” the space between the casing and the cylinder being converted into a steam chamber. Whatever method is adopted, the object is to keep the cylinder from losing its heat and to prevent condensation. The “ports” are openings through which the steam passes; by means of “slide valves” the steam is alternately admitted and expelled from each of these, so that the opening which serves to admit steam on the instroke serves as an exit for the steam on the outstroke, and the slide valves are worked from the main crank shaft by valve gear and eccentrics.

_The Valve Gear_ is the arrangement of rods that connect the eccentrics with the slide valves.

_The Piston_ consists of a circular disc of metal made to most accurately fit the interior of the cylinder; to this is connected a rod as shown, called the piston rod, which is in direct communication with the crank. It will be seen that when the steam is admitted into one end of the cylinder the pressure causes the piston to travel towards the other end; when the piston reaches a certain point (called the dead point) the slide valve shifts and the inflow of steam is changed to the other end, and this causes the piston to travel back again, and so it continues; an instroke and outstroke give one revolution to the crank and flywheel.

_An Eccentric_ (Fig. 196) is an ingenious piece of mechanism that answers exactly the opposite purpose of a crank, viz. to convert a rotary motion into a backward and forward movement. An eccentric is a circular iron disc, with the main crank shaft passing tightly through it, but the shaft does not pass through the centre; hence the term “eccentric.” This disc is encircled and revolves within an iron strap, which is attached to the valve rod or gear. It will be readily seen that as the disc revolves it gives a reciprocating movement to the rod, causing the slide valve to which it is connected to open and close the ports in the cylinder, and the object in attaching the eccentrics to the crank shaft is that the piston rod and valve rods may have an equal and corresponding action, which it will be understood is absolutely necessary.

_The Crank_ (Fig. 197), which on small engines is generally attached to one end of the crank shaft, is one of Watts’ most famous inventions (but which, however, was pirated from him), and its object is to convert the backward and forward movement of the piston rod into a rotary motion at the shaft. Disc crank plates (Fig. 198) are now getting into favour as having a steadier action, and it is to all intents and purposes a crank, but of improved form.

_The Flywheel_ is a heavy cast-iron wheel attached to the crank shaft on the opposite end to the crank itself; it serves more than one useful purpose, viz. giving great steadiness to the motion, assisting propulsion to some extent by its momentum and carrying the piston over the dead points (a dead point is the position which the piston is in when it has finished one stroke and about to return just at the time it becomes quite still for an instant, and this is called the dead point, and it happens at the end of each stroke).

_The Pulleys_ are of two kinds, fast and loose; they are light wheels about one-sixth the diameter of the flywheel, at whose side they are attached to the extreme end of the shaft. They have broad flat faces or rims, and their object is to carry the strap or belting which transmits the power from the engine to the work. The fast or driving pulley is the one that is secured to the shaft and revolves with the flywheel; the loose pulley is the one that is not secured to the shaft, and rotates loosely upon it when occasion demands; a forked arrangement transfers the belting from the fast to the loose pulley when it is necessary to stop the machinery, or vice versâ.

_The Governor_ (Fig. 199) is another ingenious and important invention of Watts, and serves a most useful purpose; it will be understood that if when an engine was working with the full strain of the machinery upon it, the belting was to break, the engine would immediately begin working at an alarming speed, most destructive to itself (this does not apply to engines, such as locomotives, that have constant attention); the governor, as the name implies, controls this. By referring to the illustration, it will be seen that as the speed of the engine increases, the faster the governor rotates (it being connected with the crank shaft); this, by centrifugal action, makes the two balls fly out, and this causes a valve in the steam inlet to partially close and so check the supply of steam from boiler to engine, thus very naturally reducing the speed.

_Lubricators_ (self-acting) are provided wherever necessary, and it is important that a motor of any description be well lubricated at its wearing parts or wherever friction takes place; this reduces the wear and tear to a minimum, and very greatly adds to the motor’s efficiency.

_Steam_ is produced by subjecting water to heat, and so causing it to evaporate; steam is commonly understood to be (by those that have not studied the subject) a white watery vapour, whereas it is exactly the reverse, it is practically as dry and colourless as the atmosphere, and possesses similar characteristics in its unlimited expansibility and compressibility; it only assumes the white vapoury appearance when it escapes in the air which is at a lower temperature than itself, as it then condenses into its original form, water; if steam was ejected into a compartment that was heated to say 220° the steam would retain its own form and be quite colourless and invisible. The expansive power of steam is put to good purpose in what is known as the “cut-off” and also in compound engines; the cut-off is an arrangement whereby the steam is cut off from the cylinder, when the piston has been impelled ½ or ⅝ of a stroke, and the expansion of the steam completes the stroke. In compound engines (which are large and have 2 cylinders) the steam, after doing service in the first cylinder, is conducted to a second of greater diameter, where by expansion it exerts a lower pressure, but on 2 or 3 times the piston area, so giving units of work equal to the first cylinder. Engines are now made with 3 cylinders, thus fully utilising this economical plan.

_Horse-power._--When steam engines first came into use they were applied to work previously done by horses which worked the mills; it was, therefore, convenient and desirable to say what number of horses an engine would supersede, hence the term horse-power, which means a capacity to produce a mechanical effect equivalent to raising 33,000 lb. one foot per minute. The indicated horse-power of an engine is the pressure exerted by the steam on the piston without allowing for friction, the indicated horse-power is therefore higher than the power that will be realised; the nominal horse-power is that which is obtained by measurement of the cylinder and piston area, and is a commercial standard, but a deficient one, and most makers’ lists now show engines which by improvements will give 1 and 2 actual horse-power higher than the nominal.