SUGAR. 



167 



ters would fiad it their interest to bring cargoes at their own 

 risk, and take return cargoes of sugar, rum, or molasses, at the 

 market price, the planter will be doubly a gainer by the system, 

 obtaining his fuel at a reduced rate, and having his trash and me- 

 gass left free as manure for the use of his cane fields. 



3. "To complete the concentration in a vacuum pan, or by 

 other means, at a moderate temperature, not hurtful to the sugar, 

 and facilitate the natural process of crystallisation, so as to obtain 

 sugar of a large and distinct grain." 



4. " To drain and dry the sugar perfectly, and to save all the 

 molasses." 



The advantages to be anticipated from these improvements, 

 superadded to an improvement in cultivation, cannot be esti- 

 mated at less, upon a moderate calculation, than from 150 to 200 

 per cent, of increase in the production of sugar, with hardly an 

 appreciable increase of labor or expense ; for we have, in the 

 first place, a gain by improved culture of, at least, two hogsheads 

 an acre in sugar, equivalent to 100 per cent. ; in the next, by em- 

 ploying improved mills and extracting the residuum, 30 per cent. ; 

 by conducting the process of manufacture more judiciously, 10 per 

 cent. ; and by the prevention of waste during the transit to mar- 

 ket, 10 per cent., making a total of at least 150 per cent. 



The common sugar-mill consists of three cylinders, tightened 

 either by wedges, if in a wooden frame, or by screws in a cast" 

 iron frame. If in an iron frame, the above-mentioned noise is 

 obviated, but the friction and loss of power is the same, which is 

 ascertainable by subsequent investigation. The cylinders or 

 rollers, which are moving either horizontally or vertically, are 

 from eighteen to twenty-four inches in diameter, with bearings or 

 ^^hafts of one fourth of their diameter. If the bearings or shafts 

 of the cylinders were of less substance, they could not resist the 

 great strain to which they are subjected when in operation. The 

 whole of the prime mover (steam-engine, water-wheel, or animals), 

 minus the friction of intermediate machinery, is transmitted to 

 the plains of these rollers and resisted by their bearings ; hence 

 the action is equal to a weight moving on low wheels of eighteen 

 or twenty-four inches in diameter, on axles of from four to six 

 inches thickness, which weight is equal to the force applied ; con- 

 sequently, if the strain is greater than the resistance of the rollers 

 or the bearings, they must be wrenched ofi", or if greater than the 

 force applied, the mill will be stopped. The power necessary to 

 move weights upon wheels, on a smooth and level surface, is in 

 proportion to the respective diameters of wheels and axles. The 

 same pull which moves one ton at a given velocity upon a wheel 

 of two feet, with an axle of six inches, will move four tons, if on 

 a wheel of four feet diameter, with an axle of six inches. Con- 

 sequently, cylinders of small diameter, with strong and substan- 

 tial bearings, are only admissible as working machines, if no other 

 mechanical means are applicable, as, for instance, in rolling out 

 metals, compressing the surface of various bodies for a glossy 



