609 



CALCULUS, CALCULATION. 



CALENDERING. 



510 



I'rinary Calculi. These, whether found in the kidneys, or ureters, 

 or bladder, or urethra, have been observed in almost every domesticated 

 animal. In the horse, a urinary calculus has occupied the whole cavity 

 of the kidney and has weighed more than a pound. It has obstructed 

 the ureters, and destroyed the horse and the ox : it has completely 

 filled the bladder of the dog, and has been shivered into a thousand 

 pieces by the sudden fall of the animal from a considerable height. 

 In the urethra also it has been productive of fatal inflammation in the 

 dog. In almost every animal sand has occasionally occupied the funchis 

 of the bladder. Minute calculi have been found in almost countless 

 numbers, or one large calculus has produced extreme pain, suppression 

 of urine, and destructive inflammation. In most of these cases means 

 have been found to allay to a certain degree the irritability of the 

 bladder, but no medicine has the slightest solvent power on the 

 calculus. The operation of lithotomy has been performed with success 

 on almost every domesticated quadruped, and that of lithotrity has 

 been effectual in the horse. 



Nearly the same constituent principles enter into the composition of 

 these calculi in the herbivorous animals. The carbonate of lime pre- 

 vails ; there are, on an average, 83 parts out of 100 of it in the urinary 

 calculus of the horse ; 87 in that of the ox, and 91 in that of the ass ; 

 the remainder is made up of subphosphafe of lime and animal cement. 

 In the hog, however, ammoniacal phosphate of magnesia is, with the 

 animal cement, nearly the sole material. In none of them has uric 

 acid been detected. 



The concretions which are found in other tissues and organs differ 

 little from those in the human being. 



CA'LCULUS, CALCULATION. The word calmlvs means a small 

 pebble, such as was made use of in teaching or practising calculation. 

 We must refer to articles of a more specific kind for different methods 

 of calculation, but as regards this individual word, we have only to 

 draw the distinction between it and mathematict. Generally speaking, 

 a calculator is taken for a mathematician ; which he may or may not 

 be. Mathematicians are sometimes fond of and skilful in calculation, 

 and sometimes the reverse of both : Euler and Wallis are instances of 

 the former ; Lagrange, according to report, of the latter. To perform 

 a calculation is to put numbers together by rules, the reasons of which 

 may or may not be understood by him who uses them. It is true that 

 a mathematician must, in the process by which he becomes such, 

 increase his power of calculation ; but whether he will ever attain the 

 expertness and correctness of a banker's clerk in the commonest 

 operation, depends upon qualities of mind which have little or nothing 

 to do with his mathematical power. It is necessary to caution our 

 readers not to take a result as mathematically correct, because it is 

 produced by a skilful calculator ; or as numerically correct, because it 

 has been worked by a good mathematician. The method of the first, 

 and the work of the second, may be wrong, without any inference 

 against either in relation to his peculiar pursuit. 



The term calculus is commonly applied to signify any branch of 

 mathematics which may involve or lead to calculation : any, in fact, 

 except pure geometry. Thus, the part of algebra which relates to 

 exponents and logarithms is sometimes called the exponential calculus. 

 The references immediately following are to those branches which, 

 without any particular reason, have permanently acquired the name of 

 . And, the word being now completely introduced, every new 

 specific development of any part of mathematics will receive the name. 

 Thus, the calculus of definite integrals, the calculus of discontinuous 

 functions, &c., are terms which are beginning to be used. In fact, a 

 calculia may now be defined as any method in which questions are 

 treated in classes by general rules. 



CALCULUS, DIFFERENTIAL. [DIFFERENTIAL CALCULUS.] 



CALCULUS, INTEGRAL. [INTEGRAL CALCULUS.] 



CALCULUS OF FUNCTIONS. [FUNCTIONS, CALCULUS OF.] 



CALCULUS OF VARIATIONS. [VARIATIONS, CALCULUS OF.] 



CALDARIUM. [BATH.] 



CALENDAR. [KALENDAR.] 



CALENDERING is a general name applied to the processes of 

 smoothing, dressing, and glazing webs orl textile fabrics of cotton and 

 linen, either to prepare them for the operations of the calico-printer, 

 or to impart the last finish to the goods before they are folded and 

 packed for the market. 



' The common domestic' smoothing-iron affords the simplest illustration 

 of the process of calendering. The mangle, which is so frequently em- 

 ployed as a substitute for the smoothing-iron, presents another form, 

 the operation of which is identical with that of some of the earlier 

 calendering machines. In the common mangle, as in the old calenders 

 constructed on the same principle, the cloths to be smoothed are 

 coiled upon smooth wooden rollers^ind laid between two hard flat 

 surfaces. The lower surface is iintnoveable, but the upper, wliich 

 it formed by the bottom of a large heavy box, is capable of being 

 moved backwards and forwards in the direction of its length, thereby 

 causing the cloth-covered rollers to roll backwards and forwards until 

 every part of the cloth wrapped upon them has received sufficient 

 compression. In a common mangle the alternate motion of the press- 

 ing-box, which is usually loaded with stones, is produced by turning a 

 winch-handle, which alternately winds and unwinds ropes extending 

 from the ends of the box to a drum or cylinder fixed over it. To 

 obviate the inconvenience occasioned by the frequent changes in the 



direction of the motion required, various ingenious devices have been 

 resorted to, by which the alternating motion of the loaded box is 

 produced by a continued motion of .'the winch-handle in one direction. 

 Being larger and heavier than common mangles, the old calenders 

 made on the same principle were often worked by a horse-wheel, or 

 some other moving power. The process of calendering was greatly 

 improved by the invention of a machine in which the pressure is 

 produced between cylinders, instead of between cylinders and flat 

 surfaces, and in which, consequently, the alternating motion is got rid 

 of ; it k is easier, too, by such a method to give a uniform and equal 

 pressure. According to some authorities the cylindrical calendering 

 engine was introduced into this country from Flanders and Holland by 

 the Huguenots, who were driven to England by persecution. The 

 rollers or cylinders were formerly made of wood ; but, as it was found 

 impossible to overcome the tendency of that material to warp and 

 crack, they are now usually made either of paper or of cast-iron. The 

 paper cylinders, which form the most remarkable feature of a modem 

 calender, are formed in the following manner. The axis is a strong 

 square bar of wrought-irou, and the body of the cylinder consists of a 

 great number of circular pieces of stout pasteboard, each of which has a 

 square hole in the centre to receive the axis, and six smaller round 

 holes at equal distances from each other, near the periphery. A strong 

 cast-iron plate, of a circular form, but rather smaller than the pieces of 

 pasteboard, and perforated in like manner, is first put upon the axis, 

 and then a sufficient number of pieces of pasteboard to form, when 

 compressed, a cylinder of the required length. Another cast-iron plate 

 is then added, and long cylindrical bolts of wrought iron, each of which 

 has a head at one end, and a screw cut upon the other, are put into 

 the six holes near the rim, and passed completely through the mass of 

 pieces of pasteboard and the end plates of cast-iron. Nuts being put 

 upon the ends of these bolts, the whole is screwed up as tight a .; 

 possible, after which the cylinder is exposed to a strong heat for several 

 days in a stove or heated chamber. By this process the pasteboard i:; 

 considerably shnmk, and while it remains hot the nuts are repeatedly 

 tightened up as much as possible. When allowed to cool the paste- 

 board is inclined to expand again, while the iron bolts contract, so that 

 the mass of paper of which the cylinder is composed becomes almost 

 inconceivably hard and dense. It is finished by very careful turning 

 in a lathe, by which the surface of the cylinder is rendered perfectly 

 true, and receives, in consequence of its extreme compactness, a very 

 high polish. Iron cylinders, which are used in conjunction with paper 

 cylinders in the same machine, are made hollow, and, for cases in 

 which the application of heat is required, are constructed either to 

 receive red-hot rollers or heaters, or to admit steam through a stuffing- 

 box in the axis at one end, and discharge it at the opposite extremity. 



The calenders now commonly employed for smoothing cotton and 

 linen goods, contain four or five rollers, mounted above one another 

 in a strong frame-work of cast-iron, which, from its ability to bear 

 the application of heat without warping, is preferable to wood. If 

 the object be simply to smooth the fabrics, the motion of the rollers, 

 which can be made to bear against one another with any required 

 degree of pressure by means of weighted levers, is so adjusted that, 

 though their relative diameters may vary, their surfaces travel with 

 equal velocity, so that no rubbing contact is produced. For some 

 goods, however, especially those intended for use in household fur- 

 niture, and in certain articles of dress, a glazed or polished surface, as 

 well as mere smoothness or evenness, is required. Such goods were 

 formerly glazed by hand upon an inclined table, with a rounded piece 

 of polished flint attached to an apparatus which enabled the operator 

 to preserve the cloth at a proper degree of tension, and to rub the 

 flint backwards and forwards with considerable force over the surface, 

 a small portion at a time. This process is now far more expeditiously 

 performed with a calender of the ordinary construction, with the 

 addition of a series of toothed wheels which cause the rollers to move 

 with different velocities, so that the surface of one will rub or slide 

 upon the surface of that adjacent to it. By the ordinary process of 

 calendering, and still more by the use of the glazing calender, the 

 round threads of which the web is composed are flattened, so that, by 

 the diminution of the interstices, the fabric is made to appear closer 

 than when it leaves the loom. Lawns, muslins, and other very light 

 transparent fabrics are calendered with a very slight pressure, in a 

 machine often worked by hand, which has the effect of smoothing the 

 goods without altering the cylindrical form of the threads. The 

 watered or " chine " goods exhibit in a remarkable way the effect 

 produced by a partial glazing, or by imparting to the round threads ,1 

 partial flattening in different directions. 



When the operation of the calender is intended to finish goods for 

 the market, it is immediately followed by folding and packing. The 

 late Dr. Ure described a very complete calendering apparatus in use 

 among the calico-printers of Alsace, to which a self-acting folder may 

 be attached at pleasure. In the large establishments of Lancashire, 

 the cotton goods are subject to immense pressure in a hydro- 

 static press, by the aid of which they are frequently made up into 

 bales with such compactness as to occupy one-third less space than 

 they could do if packed by hand in boxes. The calendering of goods 

 in the process of manufacture is closely connected with the operation:; 

 of the bleacher and calico-printer ; but the calendering of finished 

 goods is usually performed by the packer. 



