MECHANICS AND USEFUL ARTS. 127 



well-formed bricks at each stroke. The bricks are cut in the direction of their 

 bed, so that the four sides are preserved smooth, while the top and bottom 

 are slightly roughened, an effect which, with the perforation of the center, 

 secures the proper adhesion of the mortar, and consequent safety in building. 



STRENGTH OF GUTTA PEKCUA TUBING. 



Some interesting experiments recently made in Boston show an almost in- 

 credible strength hi gutta percha tubing and its value above other materials 

 for water-pipes, etc., where power to resist great pressure is required. A pipe 

 hah an inch inside diameter stood 370 Ibs. to the square inch, and burst at 390 ; 

 a five eighths inch pipe (the kind made for service pipes for the Boston water 

 works) stood till 580 Ibs. of pressure to the square inch was applied; but a 

 quarter inch pipe, made for soda fountains, stood uninjured the great pressure 

 of 1,000 to the square inch ! 



IMPROVEMENT IN THE CONSTRUCTION OF WINDLASSES. 



In the operation of almost every species of ships' windlasses or winches, it 

 is necessary to apply the rope to be heaved at right angles to the barrel of 

 the windlass ; otherwise the rope would not wind easy or even. For this 

 purpose temporary guide-posts or pulley-blocks are usually rigged, which, of 

 course, are more or less inconvenient, troublesome, and in the end expensive 

 An invention by W. N. Gesner of Fair Haven, Ct, provides a frame of iron 

 or other material, which is attached to the ends of the windlass shaft, just like 

 the bail of a kettle on a large scale. The guide-block is attached to the center 

 of the frame. The latter, it is apparent, will always be on hand when wanted, 

 and never hi the way at other tunes, for it can be thrown up or turned down 

 for use instantly, at pleasure. 







IMPROVEMENTS IN THE MANUFACTURE OF HATS. 



In the ordinary manufacture of hat bodies, several different kinds and qual- 

 ities of fur stuffs are used, the desired proportions of each being weighed by 

 the hand, and then carried to a machine, where the fibers are loosened, 

 cleaned, and thoroughly mixed together. At this stage of the process the 

 material is removed and dealt out, by hand weight, into small quantities, just 

 sufficient for single hat bodies. Each quantity is now separately passed 

 through another machine, where the mixing and cleaning operation is com- 

 pleted, and the stuff thrown by blast upon the hat former. In a machine in- 

 vented by Messrs Annesen, Pedereen, and Eees, of New York, the mechan- 

 ism is so arranged as to receive the raw material at one end, and deliver it at 

 the other ready made up into perfect unfelted hat bodies ; all the various 

 operations of selecting the desired qualities of each kind of stuff, mixing, clean- 

 ing, and weighing off the proper amount for each body, being clone in the 

 machine, without being touched by hand from first to last. It would require 

 drawings in order to convey a clear idea of the various parts. The invention 



