Ratio.

93.1

96.5

99.7

99.3

101.4

101.9

100.4

97.3

98.7

The defect in the smallest gauge is attributed to the difficulty of measuring the last drop, but somewhat may be due to a larger proportion of the rain splashing out of the funnel. The excess of the large gauges is attributed in part to dew formed in consequence of the radiation from the large surface of metal. The flange probably increases the amount by preventing escape by splashing. At 20 feet above the ground the gauge 5 inches in diameter registered considerably less than the 8-inch gauge at the same height, the ratio relatively to the gauge I foot above the ground being only 909. Long tables showing the results of the Calne experiments are given in the Reports of the British Association for the years 1869 and 1870. RAISINS [E. C. vol. vi. col. 935; FRUIT TRADE, E. C. S. col. 1082]. The recent imports have been :

the arms of Scotland or the second quarter of the English shield, is a lion rampant.

RAPHANIA, RAPHANY, a painful spasm, or convulsion, named by Linnæus from its supposed cause, eating the seeds of the Raphanus Raphanistrum, bastard radish, or charlock. Linnæus found that birds fed with these seeds died convulsed : hence the name Raphania.

RASH, RASHES, a name sometimes given to all skin disease, but more usually to such patches of superficial redness as attend scarlet fever and measles, and the urticaria, or nettle rash.

RASPS [FILE MANUFACTURE, E. C. vol. iv. col. 74].

RATANHINE, C10H13NO3 (C20H1,NO), a compound homologous with tyrosine, occurring in rhatany root. It crystallizes in colourless microscopic needles which are slightly soluble in water, and almost insoluble in alcohol or ether. It forms compounds both with acids and with metals.

the teeth of a revolving wheel in such a way as to produce RATCHET, in machinery, a hinged catch, which falls into momentary stoppages, without allowing the wheel to run back in the opposite direction.

RAZOR MAKING [CUTLERY, E. C. vol. iii. col. 364]. term in medicine, to indicate a state of recovery or excitement REACTION (from re, again, and ago, to act), a common following upon a previous depression or collapse, or a return of have the chills and shiverings that result from exposure to cold, followed by a reaction, which consists not merely in restoring a state of health, but in setting up a feverish condition. Again, an inflammation which has passed away under the lancet will return with even increased force when the effect of the bleeding has passed away.

an inflammation after it has been reduced for a time. Thus we

REAGENT, in chemistry, a term synonymous with test. REAPING AND MOWING MACHINES. The greater breadth of harvest is now cut by machinery. The manufacture of mowing and reaping machines constitutes a large trade, some makers turning out several thousand machines annually. They

in the details of construction; but the early patents having expired, and become public property, the working parts copied from them have a close resemblance to each other in principle, as the finger-bar, knife, platform, rakes, &c. The annexed four engravings represent the best machines at present in use. Fig. 1 is the reaping machine of the Messrs. Burgess and Key. It represents a large class, known as "self-rakers," or "self-delivery reapers," the first of which was introduced from the United States of America, in 1861, by Samuelson and Co., Banbury; and Ransomes and Sims, Ipswich. It is sometimes termed the D'Orsey reaper, after the American inventor. Its peculiar novelty is the undulating cam, on a high standard, for guiding the rake arms so as to reel the standing corn on to the knife, and to sweep the cut corn off the platform, leaving it in sheaves at the side. The original machine has been improved upon by different makers, and of the improved machines Fig. 1 is the simplest and most successful example. It will be seen from the engraving that the knife gear is inside the main wheel; and the rake gear outside; that the crank and connecting rod for actuating the knife work low, so that in crossing centres the dead points are in a line, consequently the thrust on the one side, and the pull on the other are equal, the velocity and cutting power of the knife are also equal. It is otherwise when the crank works high above the knife, as the length of the two strokes is unequal, and also the velocity and cutting power of the knife. It will also be seen from the engraving that the knife and rake standard are in a line with the axis of the main wheel, so that the fulcrage is perfect and free from much antagonistic action, wear, and tear, otherwise experienced. The grain wheel is also nearly opposite the main wheel, so that it does not "plough" in turning, backing, and in cutting curves, laying corn two ways,

Fig. 2.-Wood's Low Standard Self-raker Reaper.

nually on the increase. It is made by Walter A. Wood, of London and America, and was introduced for harvest, 1873. It is a light machine, weighing only 9 cwt. 12 lb., width of cut 5 feet, and is similar in most of its details to the heavy machine with open wheel introduced in 1871. It has four rakes, but each alternate rake can be converted into a reel when required. The grain wheel is opposite the main wheel, so that ploughing is avoided. The cutter bar is nearly in a line

&c. When the axes of the grain wheel and main wheel are not in a line, the former ploughs in soft land, so that cutting becomes impracticable. The weight of the driver, whose seat is outside, and the rake, gear, and standard reduce the weight on the grain wheel. The weight of the driver and platform also counterbalance the pole, &c., thereby relieving the horses of undue pressure on the neck. When first introduced, in 1870, the rake arms were without cam guides; but as the path described by the rakes and reels was that of the frustum of a cone, the platform required a corresponding curve, so that the rakes had to raise the whole crop cut some six inches, thereby consuming more power than when made with a cam guide and level plat

with the axle of the main wheel, and the height of the cut is adjusted vertically at both sides by a common key-lever. The knife works free in the fingers, so that dirt cannot accumulate. The driver's seat is outside. In the drawing it is partially covered by two of the rakes; but a portion of it is seen behind the vertical lever: the driver is out of harm's way, and yet has entire control of his machine and horses. By the use of a lever the points of the guards can be elevated or depressed as the nature of the crop requires, and the mode of throwing out of and into gear is perfect. The gearing for driving the knife is inside and covered to protect it from dirt, straw, &c., and all the bearings are supplied with self-acting patent spring

oilers. The rake gearing is also inside, and has been greatly simplified as compared with the original, and the difference in the mechanism and mode of working the rakes as compared with the high standard class will readily be understood from the two engravings, Fig. 1 and Fig. 2. Thus in the latter the two opposite arms are connected by a rod or link, but each is hinged independently at the standard, so that, in principle, they work like the oar of a boat, each having a short lever, like an oar handle, which is actuated by a small solid cam, totally different from the guide-way cam of Fig. 1. The main wheel of the machine (1871) turns on friction rollers instead of an axle; the knife gear is outside, and the connecting-rod works through the wheel. The rake gear is inside, as in Fig. 2, and driven by a screw which gives it a smoothness of action not attainable by cog-wheel or pitch-chain gearing. Another peculiarity of Wood's machines is the control which the driver has in adjusting the velocity of the knife and rakes to suit the difference of pace of draught cattle, as oxen and horses; or the requirements of different crops and seasons. This is of much importance on the continent of Europe, where oxen are largely used, and crops not very uniform.

Fig. 3 is an engraving of Burgess and Key's combined reaper and mower. There is a large number of this class of machines now in use, and in the details of mechanism there is considerable diversity, but in their general appearance they more closely resemble each other than the self-rakers. In the above machine the knife gear is between the driving-wheel and the platform, as in Fig. 1 and Fig. 2; but in most machines it is between the two main or carriage wheels, as in Fig. 4. The peculiar characteristic of the machine as a reaper is the sparred tipping platform, the raker's seat over the driving-wheel, and the bringing of the standing corn on to the knife, and the leaving of the cut corn behind in

a broad swathe the breadth of the platform by means of a long handled rake. What is done by the rakes and reels of Fig. 1 and Fig. 2, is in Fig. 3 done by a man with a single rake the breadth of the platform, the difference of results being that in the former two the sheaves are left at the side, out of the way of the horses next time; whereas in the latter, they are left behind, and require to be bound up before next cut. The second seat is for the driver. By removing the platform and raker's seat, and putting on a lever for lifting the cutter bar the machine is converted into a mower, with some slight difference owing to the knife gear being differently situated, agreeably to what has already been stated.

MOWING MACHINE. Fig. 4, represents a mowing machine of the Messrs. R. Hornsby and Sons, Grantham. At the last reaping and mowing machine trials of the Royal Agricultural Society of England, held at Manchester, 1869, it gained the first prize. The engraving is from a photograph of a greatly improved mower got up for 1873. The substitution of steel and wrought iron for cast iron in the construction of the new mower, increases strength, whilst it reduces weight and draught. The gain is thus twofold, for the machine, by standing firmer up to its work, does more work for a given power applied, and with a reduction of wear and tear upon the working parts. The engraving is so plain as to require little explanation. The fingerbar hinges on the crankshaft, so that the knife cuts freely over undulating surfaces. The crank is low, as in the preceding reapers, giving an equal thrust and pull, the velocity and cutting power being thus equal. All the other movements, as the throwing out of and into gear, turning at the headlands, &c., are highly satisfactory. So is the draught of the machine.

RECEPTACULUM CHYLI, in anatomy, the enlargement of the thoracic duct which is seated close to the aortic opening of the diaphragm. It was discovered by Pecquet.

RECIPROCAL POLARS [POLARS, RECIPROCAL, E. C. S.]. RECTO AND VERSO (Latin, recto, right, regular; verso, to turn). Recto is the first or right-hand page of a book, or folded sheet of paper: verso, the opposite, second, or left-hand page. In early printed books only the right-hand pages were numbered; but, as it was convenient to distinguish the num

bered from the unnumbered page opposite it, the former was termed the recto and the latter the verso: hence, such references as "fol. 253 recto," "150 verso."

RED DYES AND PIGMENTS. The chief substances used in dying spun and woven goods are madder, cochineal, and lac dye, producing various tints of red and scarlet. More fugitive red dyes are obtained from Brazil wood, safflower, and orchil. Important additions have recently been made to the list by the discoveries relating to ANILINE, ALIZARINE, and other coal-tar products [see those headings, E. C. SJ. The selection of substances, and the modes of treatment, vary according as the fibres, yarns, and textiles are of cotton, wool,

Fig. 4.-Hornsby's Mower.

silk, or linen. Red pigments, for the use of artists, house painters, &c., comprise chrome red, Armenian bole, Indian red, realgar, red chalk, red lead, red ochre, red orpiment, Venetian red, vermilion, lakes, carmines, and some others. REFLECTION and REFRACTION, EXTRAORDINARY ATMOSPHERIC. Under HALO, E. C. S. col. 1220, references are given to certain natural phenomena, dependent on extraor dinary atmospheric reflection or refraction. MIRAGE [E. C. vol. v. col. 701]; AERIAL IMAGES [E. C. vol. i. col. 115]; and FATA MORGANA [E. C. vol. iv. col. 29]; are not here accounted for, but they are noticed under FATA MORGANA [E. C. S. col. 971], and MIRAGE [E. C. S. col. 1567].

REFRACTION, CONICAL. While studying the phenomena of biaxial crystals, Sir W. R. Hamilton "reached the unexpected conclusion that in certain circumstances the contact would not be mere points. The efficient or determining contact in these special cases is that of four planes, and he discerned that they could not touch the surface of the wave in two points, but in an infinity of points, constituting what may be termed a small circle of contact." Hence he predicted that there would not be two emergent rays, but a cone of rays diffused from a point, and appearing as a luminous circle. The experimental verification was accomplished by Professor Lloyd, and two separate classes of phenomena, as predicted, were producednamely, exterior and interior conical refraction: the ray in the one case issuing as a cone, with its vertex at the surface of emission, and in the other as a cylinder, having been converted on entering the crystal into a cone, whose vertex is at the point of incidence. Further details are given in Nicol's 'Cyclopædia of the Physical Sciences,' 1860, p. 744.

REFRIGERATORS, REFRIGERATING. The processes of cooling or lowering the temperature of various solids, liquids, and gases may be grouped in two classes: those which do not involve change of state; and those which depend on the congelation of water into ice. Various illustrations of both classes are treated under COOLER, COOLING, E. C. vol. iii. col. 183; FREEZING APPARATUS, ib. vol. iv. col. 208; FREEZING MIXTURES, ib. col. 209; ICEHOUSES AND ICE TRADE, ib. vol. iv. col. 819; ICE TRADE, E. C. S. col. 1332. See also, for the cooling of malt

liquors and spirits, BREWING, and DISTILLERY, in E. C. and E. C. S.

REGELATION, the name given by Dr. Hooker to the phenomenon, observed by Faraday in 1850, of the freezing together of two pieces of melting ice when brought into contact. Whenever two pieces of thawing ice are brought together regelation commences. Faraday, in illustrating the phenomenon, placed two pieces of ice in warm water, and on pressing them together they immediately congealed together, and were lifted out as one piece. It is necessary, however, that the two surfaces thus brought into contact be in a melting state, or regelation will not follow. When the temperature is below the freezing point, and the surface of the ice remains dry, regelation does not take place. The pressure of two pieces of ice together at a temperature of 32° Fahr. will, however, cause liquefaction at the points of contact; the water which escapes is lowered beneath the freezing point, and regelation commences the moment the pressure is removed. Dr. Tyndall, who in his lectures at the Royal Institution, has repeated the more remarkable of Faraday's experiments along with others equally remarkable of his own, showed this very strikingly in the following beautiful experiment by Mr. Bottomley :- "Let us," said he, "support on blocks of wood the two ends of a bar of ice 10 in. long, 4 in. deep, and 3 in. wide, and let us loop over its middle a copper wire, onetwentieth, or even one-tenth, of an inch in thickness. Connecting the two ends of the wire together, and suspending from it a weight of 12 or 14 pounds, the whole pressure of this weight is concentrated on the ice which supports the wire. What is the consequence? The ice underneath the wire liquefies; the water of liquefaction escapes round the wire, but the moment it is relieved from the pressure it freezes, and round about the wire, even before it has entered the ice, you have a frozen casing. The wire continues to sink in the ice; the water incessantly escapes, freezing as it does so behind the wire. In half an hour the weight falls; the wire has gone clean through the ice. You can plainly see where it has passed, but the two severed pieces of ice are so firmly frozen together that they will break elsewhere as soon as along the surface of regelation." Professor Tyndall showed farther, as one of the consequences of regelation, that ice might by sufficient pressure be moulded into almost any desired shape. By means of suitable moulds and the action of a hydraulic press he formed spheres, lenses, and cups-the ice being by the pressure crushed into minute fragments and forced into the moulds, where the particles soon became reunited by regelation into a compact body.

Professor Thomson thinks that regelation is due to the liquefaction which results from the pressure of the two pieces of ice. "When two pieces of ice are pressed together, liquefaction takes place; the water spreads out around the points of pressure, and when released refreezes, thus forming a kind of cement between the pieces of ice." Faraday's theory is thus stated by Tyndall (Forms of Water,' p. 173): "When the surfaces of two pieces of ice, covered with a film of water of liquefaction, are brought together, the covering film is transferred from the surface to the centre of the ice, where the point of liquefaction, as before shown, is higher than at the surface. The special solidifying power of ice upon water is now brought into play on both sides of the film. Under these circumstances, Faraday held that the film would congeal, and freeze the two surfaces together." For the connection of regelation with glacier motion, we refer the reader to § 61 of Dr. Tyndall's volume just quoted.

REGENERATIVE FURNACE. In all ordinary forms of furnace there is waste of heat-(1) from imperfect combustion; (2) from the large amount of heat carried off by the waste gases in the chimney. To secure, even approximately, perfect combustion, the quantity of air admitted to the furnace must greatly exceed the quantity chemically necessary for combination with the fuel. The effect of this is, not only to increase the waste of heat in the chimney, but in certain operations, in which the intensity of the heat is of the highest importance, it is specially prejudicial, because the heat generated being distributed amongst all the gaseous products passing through the furnace, is thereby diluted and the temperature lowered. About 1856 Mr. Frederick Siemens proposed the use, in connection with furnaces, of regenerators," contrivances orginally designed to obviate the waste of heat in air-engines, and since then, in conjunction with Mr. C. W. Siemens, the regenerative furnace has become a most important means of obtaining a high temperature in many manufacturing and metallurgical operations.

In the regenerative furnace, the fuel is first converted into gas by distillation at a high temperature, in a part of the system

ARTS AND SCI. DIV.--SUP.

called the producer. The gas obtained is conveyed through flues, in which the mixture with air is carefully prevented, to the regenerator. Here its temperature is raised in a way to be described presently. From the regenerators it passes to the furnace proper, where the heat is required, and where it first mixes with a properly regulated supply of atmospheric air. Where the highest possible temperature is required, this air must also have been heated before reaching the furnace by passing through regenerators. In the furnace proper, the gas and air combine, and the heat due to the chemical action is liberated. From the furnace, after having accomplished the operations in which the heat is required, the gases pass again to a set of regenerators, in which they abandon their surplus heat before they pass away into the air.

The producers are often placed below the surface of the ground, partly to facilitate the supply of fuel, and partly because the draught through them can then be most easily secured. The producer consists of a large furnace with a steep inclined grate, into which fuel is admitted from the top. The fuel slowly descends along the inclined grate, as the distillation proceeds, the distillation being due to a slow combustion going on at the fire-grate. At the upper part the fuel parts with its volatile constituents, such as hydrocarbon gases, ammonia, and water. The carbon which remains combines with the entering air, and forms carbonic acid near the grate. But this carbonic acid, afterwards passing through a mass of red hot carbon, is converted into carbonic oxide. The draft is so regulated as to secure the conversion of the fuel into combustible gases, with the perfect combustion of only a very small part of it. The gas obtained in the producers has been found to consist of61.5 per cent. 23.7

Nitrogen

Carbonic oxide Hydrogen

Carbonic acid.
Carburetted hydrogen 2.2
Oxygen.

Each ton of coal produces 64,000 cubic feet of gas, the volume of which would be increased about six times when heated to 3,000°; but, in reality, in consequence of chemical changes which take place, the volume, when heated, is greater.

The regenerators consist of chambers filled with firebrick, arranged so as to leave passages between them. They require always to be arranged in pairs. Into one regenerator of the pair the waste gases of the furnace are admitted at a temperature of 3,000 or more. The hot gases percolate through the brickwork and heat it, thus abandoning their surplus heat. When this regenerator has been sufficiently heated, the waste gases are turned into the second regenerator, and the gases from the gasproducers are passed through the one which has been heated. Entering it at a comparatively low temperature, they are heated, re-absorbing the heat abandoned by the waste gases, and carrying it back into the furnace. In about half an hour, the direction of the currents is again reversed, the waste gases being passed again through the first regenerator, and the gas from the producers being passed into the second, which in the interval has been heated. By continued reversals, the heat of the gases entering the furnace is maintained, while that of the waste gases is stored up, ready to be given back to the furnace. A pair of regenerators for heating the air to be supplied to the furnace can be worked in precisely the same way. Very simple arrangements of valves serve to reverse the directions of the currents whenever necessary.

The perfection of the action of the regenerator is secured in this way. The waste gases at a high temperature, entering at the top, pass gradually downwards over the firebrick surfaces. The top layers of firebrick are raised to a high temperature, but the gases, passing downwards, meet constantly cooler surfaces of firebrick. In time, of course, the whole regenerator might be heated to a high temperature, but before this takes place the currents are reversed. Then the gas from the gas-producers, entering at the lowest and coolest part of the regenerator, and passing upwards through layers of constantly greater temperature, is gradually and regularly heated up to the proper temperature for entering the furnace.

When the heat of the furnace is not abstracted continually by charging cold materials into it, the temperature necessarily rises after each reversal of the current, for the waste gases carry off only a small fraction of the heat generated by combustion in the furnace. Hence the temperature which may be attained, by the

5 Y