MECHANICS AND USEFUL ARTS. 79 



of the machine ; but the -weight must at all times, when in operation, be 

 allowed to rest on the diggers. In short, the main wheel and the whole 

 machine must be allowed to sink down into a ditch, or rise to the surface, 

 while the carrying wheels simply run lightly on the surface at the sides. 

 This end is accomplished by bending the axle into the form of a large crank 

 at each side, and releasing it from all connection with the machine, except 

 that of passing loosely through the centre. A catch is provided, by which 

 the attendant (who is supposed to be grasping a pair of handles in the 

 rear) may make the connection a fixed one at pleasure; and when desiring 

 to leave the field and travel the road, the weight may, by this means, be 

 thrown entirely upon the carrying wheels. 



ON THE EMPLOYMENT OF WATER IN FILLING UP DEEP BORE HOLES 



IN BLASTING OPERATIONS. 



In working the great deposit of magnetic iron ore which occurs under 

 peculiar circumstances in the granite at Moravitza, in the Banat, it has 

 been found necessary, in consequence of the hardness of the rock and ore, 

 to use bore holes, from two to two and a half inches in diameter, and 

 thirty-six to forty inches deep. The packing of such holes with clay be- 

 ing a very tedious operation, Mr. A. Keszt endeavored to substitute water 

 for the clay, with considerable success. One of Bickford's safety fuses, 

 which burns in water perfectly, is attached to the cartridge, and fastened 

 with thread ; this cartridge is let down to the bottom of the hole, and 

 about one and a half to two inches of clay firmly packed over it, the re- 

 mainder of the bore, nearly to the top, being filled with water. In the 

 case of very oblique bores, where the pressure of the water upon the bottom 

 was small, he plugged up the orifice of the bore with a plug of wood, 

 driven with considerable force into it, through a slit in which the fuse 

 passed. More recently still he had used, instead of a small quantity of 

 clay first introduced, to keep the cartridge from becoming wet, a mixture 

 of tar and pitch, which most effectually preserves the powder from damp. 

 Great numbers of trials have convinced him that the blasts fired with this 

 arrangement lose nothing in force, whilst there is a great saving of time, 

 and, consequently, of expense. Osterr. Zeitschrift far Ber-u-Huttemcc- 

 sen. 



MARTIN'S IMPROVED JACQUARD LOOM. 



In Martin's new Jacquard machine, the object had been to substitute 

 for the heavy cards a sheet of prepared paper, punched with given aper- 

 tures, like the cards of the old machines ; but instead of being a series of 

 pieces, two and one half inches wide, laced together, the punched paper 

 formed a continuous band, only three-quarters of an inch wide, thus so 

 diminishing the bulk that the weight of the new band, as compared with 

 that of the old cards, was in the proportion of one to eleven. The method 



