Reports of Judges. 57 



REPORTS OF JUDGES. 



Every article shown in the fortieth exhibition was examined and 

 reported upon by competent judges appointed for that purpose. Each 

 report, or so much thereof as was asked for by the exhibitor interested, 

 has been engrossed and signed by the president and secretaries of the 

 Institute, and presented to such exhibitor. 



To give all these reports in full would occupy space in the volume 

 of Transactions which must be reserved for a statement of the opera- 

 tions of other branches of the Institute. A few reports on machines 

 and processes of unusual merit are hereto annexed, together with 

 careful records of experimental tests and a summary of their results, 

 made by order of the board of managers. 



EEPORT ON BENJAMIN CHEW TILGHMAN'S SAND- 

 BLAST PKOCESS. 



To the Board of Managers : 



Gentlemen. — After a full and impartial examination of the speci- 

 mens of cutting hard substances by the sand-blast process, the under- 

 signed judges report, that the process is designed to execute orna- 

 ments, inscriptions in intaglio or relief, or complete perforations, in 

 any kind of stone, glass and other hard and brittle substance ; or to 

 cut deep grooves in natural rocks, in order to facilitate the process 

 of quarrying ; or to make circular incisions around the central mass 

 of rock in the process of tunneling ; or to remove slag, scale and sand 

 from the surfaces of metal castings ; or to clear the interior surfaces 

 of boilers or boiler tubes of incrustations ; or to cut ornaments or 

 types from wood as well as from stone ; or to depolish the surface 

 of glass, producing, by the use of stencils or other partial protections, 

 such as the bichromatized gelatine of photographic negatives, every 

 variety of beautiful figures, including copies of the finest laces and the 

 most delicate line engravings ; or to prepare copper-plates in relief for 

 printing, by making gelatine photographic pictures upon smooth sur- 

 faces of resin or pitch, cutting them out by the blast and afterward 

 molding from them and electrotyping the molds. 



