Indeed, the whole changes necessary to convert a smoothing into a glazing calender, consists merely in accelerating the rotatory velocity of the main cy linder A, whilst those of the other cylinders remain unchanged. The shifting of one wheel upon the and the addition of four smaller whed, or pinions to the engine,. is entirely adequate to pro. duce this effect ; and, in point of fact, this is the whole extent of the improvement. The extent of alteration in the relative velocities, of course rep. late. the quantum of friction, and the extent of eon which is given to the cloth ; and this must be varied in proportion to the strength and density of the fabric to be glazed. As an illustration of the principle, let it be supposed, that a friction of one inch is to be communicated in every three inches of cloth, and the effect will be attained in the manner represented by the glazing calender, fig. 2. Plate XLV.
Let the wheel on the main cylinder A. be reduced to thirty-two teeth, and let the power be so applied, that its own velocity of rotation shall be increased until it makes three revolutions where it formerly made only two. Then the diminished wheel, which has been substituted, in place of direct operation, will communicate rotation to the iron cylinders BB, by the intervention of two intermediate pinions DD, the diameters and teeth of which are entirely discre tionary, as they affect only their own respective ve locities, and not those of the cylinders in general.
Notwithstanding the extreme simplicity of this improvement, it has given very universal satisfaction, and, as the time of the patent will very shortly ex pire; there is little doubt of its universal adoption, to the entire supersession of the common and tedious operation of lazing.
For dressing muslin., gauzes, lawns, and other goods of the light and transparent fabrics, a smaller species of calender, represented by fig. S. is em ployed. It consists of only three cylinders of equal diameters (generally about six inches), and is easily moved by a common winch or handle at F. The mid cylinder is iron, and the others wood or paste board. They are Of equal diameters, and are moved with equal velocities by the small wheels at E. This machine is always used in a cold state.
The folding of cloth is so entirely regulated by fashion, that no precise rules can be laid down for its regulation. In, as all the different wimp factures of cloth imported from other countries, the original foldings have been copied to complete the resemblance. In the infant state of
imitation there was probably some policy in this, but the continuance may be ascribed almost exclusively to the power of habit. Preservation and portability are the main requisites to be attained by folding; and these are attained by subjecting the cloth, when folded, to a very powerful compression.
To communicate this, very strong presses are em ployed, of which various kinds are in use.
The capstan press, which is the most usual, is re presented by fig. 4. at G. They are now generally constructed of cast iron, the screw and handle ex cepted, which are malleable. They are tightened to a certain pressure, by merely using a lever of 10, 12, 16, or more feet in length, to turn the screw. When greater compression is required, the end of the lever is connected by a strong rope or chain with the capstan at I, which is heaved round by handspikes until the desired compression be obtain ed. The pieces of cloth are separated in the Fos by smooth wooden boarthi and folds of that species of glazed .pitsteboard, which, from its application to this very use, has acquired the appellation, oolong stationers, of pressing-paper.
Water-presses, upon the forcing principle of Mr Bramah, or acted upon by the pressure of a column of water, are also employed ; but the latter depend much on local situation, and cannot easily be ap plied in large towns like Manchester or Glasgow, where the chief command for calendering exists.
To the mechanical art of calendering, it is found expedient, in the eitended states of commerce, to add many of the operations of packing, sheeting, and preparing goods for shipment, and these generally form a branch of the establishment. In order to suit the great extent and variety of manufacture practised in Britain, and to adapt these to the pre valent tastes and views of the extensive range of consumers to be supplied, a multiplicity of foldings or lappings have been necessarily adopted, few of which, probably, possess much claim to entire origi nality. The high, and perhaps preeminent, station which the productions of the British looms have gra dually attained, seem to be rather the effect of assi duous and enterprising industry, than of great ori ginality of invention, or precedence in mechanical improvement. • Certainly, she can, at the utmost, boast of only one raw material, from which cloth is manufactured, as peculiarly indigenous.