320 REPOKT ON NATIONAL MUSEUM, 1886. 



(6) Square drove. — The square-drove surface is made with a wide steel 

 chisel with a smooth edge, called a drove. It is quite commou to use 

 this style of fiuisli as a border to the rock-face or pointed surfaces in 

 many kinds of exterior work. 



(7) Tooth chiseled. — This finish is produced by means of a wide steel 

 chisel with an edge toothed like that of a saw. This and the square 

 drove are used principally upon limestones, marbles, and sandstones, 

 the granites being too hard to be cut in this manner. 



(8) Smvcd face.— This is the surface of the rock as left by the saw; 

 the saw use<l for the purpose being a thin smooth blade of soft iron fed 

 with sharp sand or chilled iron. This and the following styles, although 

 possessing distinctive characteristics easily recognizable by the eye, are 

 of such a nature that their likenesses can not be well rei^roduced on 

 paper. Hence no attemj^t at illustration has been made. 



(9) Fine sand Jinish. — To produce this finish the chiseled or sawn sur- 

 face of the marble is rubbed smooth by means of a block of stone and 

 fine wet sand or on the machines yet to be described. 



(10) Pumice Jinish. — This is a very smooth but unpolished surface 

 produced by smooth rubbing with pumice or Scotch hone. 



(11) Polished surface. — Two kinds of polished surfaces are made — the 

 acid gloss and the putty gloss. For either the surface of the stone is 

 made as smooth as possible by means of sand, or emery, and pumice, or 

 hone, after which it is rubbed with moist woolen cloth and oxalic acid, 

 or polishing putty. The latter produces the best and most lasting gloss, 

 but requires more labor. Frequently the two methods are combined, 

 especially in tombstone work. 



G.— MACHIiS^ES AND IMPLEMENTS USED IN STONE WORK- 

 ING. 



DRILLS AND DRILLING MACHINES. 



Of the many machines that have from time to time been invented for 

 working stone we can here mention only the principal ones that are to- 

 day in actual use. 



Drills. — The old-time method of drilling by means of a flat pointed 

 drill called a "jumper," which is held by one workman while others 

 strike upon it alternate blows Avith heavy hammers, although still in 

 use in many quarries, has been largely superseded by steam-drills of 

 various kinds. A simjile form of the steam-drill, and one now in very 

 general use, is that shown in the accompanying figure (page 321). The 

 drill proper is fastened directly to the piston, which can be inclined at 

 any angle, thus fitting it for ordinary quarrying or for tunneling. It is 

 driven either hy steam or by compressed air. A different adaptation of 

 the same principle is employed in the channeling and gadding machines 



