An improvement on the chain rakes is the so-called porcupine machinery, which has perhaps been more extensively adopted than any other form of mashing apparatus. This mashing apparatus consists of a series of rakes carried by curved arms fixed to a pair of horizontal shafts, placed one above the other ; the rakes being arranged so that as the shafts revolve they pass each other, and thoroughly turn over the goods in the, mash tun. The inner ends of the horizontal shafts are carried by plummer blocks attached to brackets, which encircle the central vertical or driving shaft, the lower end of which rests upon a suitable beariog at the bottom of the mash tun. The outer ends of the rake shafts rest in bearings carried by a kind of frame, which is connected by tie bars with the brackets encircling the central shaft, and supported by a pair of rollers bearing on the rim of the mash tun. Each shaft carries a sliding clutch for connecting it to its pinion, and these clutches are both worked by one lever, so that they cannot be engaged simultaneously. One of the pinion shafts extends inwards towards the centre of the mash tun, and at its inner eud carries a bevel wheel, which gears into a bevel pinion on the central shaft, this piuion being about one-third the size of the wheel. The rake shafts also carry bevel wheels, which gear into equal sized-wheels on the vertical shaft, the pairs of wheels being arranged so that the two rake shafts are both caused to revolve in the same direction. From the vertical shaft, motion is communicated to the rake shafts, and a slower motion to one of the shafts carrying a pinion gearing into the circular rack. From this shaft a still lower motion is communicated to the other shaft. When one of the rack pinions is thrown into gear with its shaft by means of its clutch, the whole apparatus will be made to travel slowly round the mash tun, and the rakes will he brought to bear upon the whole of the goods. The direction of motion of the apparatus, and the speed at which it is caused to travel, will depend upon which pinion is thrown into gear. This arrangement of travelling gear is similar to that adopted with chain rakes. The mashing apparatus here described has been very largely adopted ; it is in some breweries used alone, and in others with a separate mashing machine, such as Steel's. In most cases the arms and teeth are of wrought iron, but the teeth are sometimes of wood, and occasionally both the teeth and arms are wood. At the City of London Brewery, where mashing machines of this kind are in use, the central shafts are fitted with teeth, which act upon the central portion of the goods not touched by the revolving ra,kes ; and at Charrington's brewery, where there are three mash tuns 18 ft. in diameter, and capable of mashing 100 qrs. each, these porcupine machines are also used, the rake shaft being naade to extend across the diameter of the tuns. Another arrangement for stirring the goods within the tun, consists of a central shaft carrying two curved arms, which work close to the false bottom of the mash tun, and act upon the lower portion of the goods only. The mixing of the malt and water is effected by a Steel's masher before the goods enter the tuu.
Brewers are now of opinion that it is better to effect the mixture of the malt and liquor in detail as these enter the mash tun, than to deal with the goods in a mass. Separate mashing machines have consequently been adopted. The masher designed by Steel, of Glasgow, has probably been more extensively used than any other. This masher is of exceedingly simple construction. It consists merely of a cylindrical casing, within which revolves a shaft provided with a number of radial arms. The casing is open at one end and closed at the other, the shaft passing through a stuffing-box at this closed end, and provided outside with fast and loose helt pulleys. The grist
and liquor are admitted to the casing by branches at the closed end, and as they pass through to be delivered into the mash tun from the open end of the casing, they are thoroughly mixed together by the action of the arms on the revolving shaft. The branch through which the malt enters is fitted with a regulating slide, and both the main casing and branch are fitted with hand boles which give access for cleaning. The water branch communicates with the side of the casing, and is fitted with a cock. In some mashers, there is no slide for regulating the supply of the malt, the latter being received direct from a small hopper placed below the malt mill. The casing of the masher, instead of being cylindrical, tapers slightly in its diameter, being reduced towards the end from which goods are delivered into the mash tun ; and to further delay the progress of the mash through the machine, the central shaft is fitted at intervals with flat arms, or oars, in addition to the usual circular arms. The liquor is delivered into the casing from the branch through two openings opposite each other, these openings communicating with a passage cast around the branch. Arrangements are made for admitting either hot or cold water through the openings. The central shaft of the masher is driven by bevel gearing.
In nutuerous breweries, Steel's mashers are used alone, and the whole of the mashing is effected by them ; in other cases they are used in combination with larger mashing apparatus placed in the mash tun. Where separate mashers are alone employed, it is the practice to make but one mash, and to sparge the remainder of the length of liquor ; where mashing appliances are provided within the tun, a series of mashes may be made, the goods being turned over during each mash. To ensure a steady supply of malt to the mashing machine, and to prevent balling, a malt feeder has been designed. This feeder is placed between the grist shoot and the mashing machine. It consists of a casing containing a drum, which has an oscillating motion imparted to it by an eccentric fixed on the central shaft of the mashing raachine. On each side of the oscillat ing drum are flaps, the position of which regulates the quantity of malt passing through ; the drum, as it oscillates, lea,ving an opening between it and each flap alternately. Fig. 303 illustrates Steel's masher as arranged for pale and black malt mashing combined. F is the ground-malt hopper ; E, the outer masher or saturator ; D, the mash tun, with its revolving rakes arranged as previously described ; B, the pipe conveying the wort from the mash tun through the infuser ; H, the black malt infuser and rakes ; o the pipe from the infuser to the copper, where porter is being made. When the large mash tun D is oharged with pale and brown malts, the proportion of black malt required for the brew is mixed with water in the small mash tun II, termed the infuser, at a temperature equal to that of the goods in D. The infusion of the black malt depends on the time of infusion of the other malts ; when these are infused sufficiently, and ready to be run off, the tap in the pipe 0 is opened as well a,s that in the pipe communicating betwe,en D and H. The half-pale extract from the large tun D is used to dissolve, absorb, and carry off the colouring matter from the black malt in H. Thia plan haa been found economical and certain, as it gives all the colour that can be obtained by mixing the pale, brown, and black malts together, in addition to the quantity lost in dyeing the graina. The pale and brown grains becoming whiter by this mashing, aro worth more in the market. The only uncertainty that can arise is from the wort losing heat, and this can be prevented by steam jacketing the pale aud brown wort pipes.