476 SEC. 12. APPLIED MECHANICS. 



attended by foresters who wish to become qualified for the post of manager 

 of wood- working establishments. For these lectures, diagrams of all sorts" of 

 tools and machinery for wood- working, are prepared. The examples shown 

 form only the first part of the series. 



2O57. Model of Lever Plough, with 6 shares, for plough- 

 ing by steam. (Fowler's system, reduced to one-tenth.) 



M. Digeon, Paris. 



2059. First Type-distributing Machine, invented by 

 Alexander Mackie. John Maclauchlan. 



591. Small Wooden Model of Prof. Colladon's new Air 

 and Gas Compressors (patented), used for the great St. Gothard 

 Tunnel. Prof. Daniel Colladon, Geneva. 



This system of compressors refrigerates air and gases simultaneously with 

 the compression, and all the movable parts are kept cold, whatever may be 

 the rapidity and force of compression. This system has been applied to 

 several industrial purposes. It is the system of air compressors used exclu- 

 sively in the boring of the great St. Gothard tunnel (length 14,920 metres). 

 At the extremity of this tunnel 30 of these compressors give 40 cubic metres 

 of air per minute, under the pressure of seven atmospheres, for the aeration of 

 the tunnel, and the working of 60 boring machines and other apparatus, and 

 eight other compressors supply air at 14 atmospheres for compressed air 

 locomotives. See 2O6O. 



2060. Drawings of the air compressors on the Colladon 

 system, employed in boring operations at the St. Gothard. 



Prof. Daniel Colladon, Geneva. 



2061. Models, Twenty-seven, for teaching machinery, exe- 

 cuted by M. Schroder, of Darmstadt. Prof. Pigot, Dublin. 



2065. Hook's Universal Joint, by which a shaft can be kept 

 in rotation at any angle. Elliott Brothers. 



2067. Steam Thermometer, for testing temperature of steam 

 in the supply pipes. Elliott Brothers. 



It consists of a thermometer the bulb of which dips into an iron cup con- 

 taining mercury and oil. By this means the bulb is protected from breakage 

 by pressure, and the thermometer can be removed at any time without letting 

 off steam. 



2068. Air Bell. 



The Committee, Royal Museum, Peel Park, Salford. 

 An apparatus consisting of a metal tube 30 feet long, with a percussion 

 pump at one end and a clapper at the other, which rings a bell whenever the 

 piston is struck. [Supposed to be the invention of the late Mr. Gavin 

 M'Murdock, of Soho, Birmingham.] Made by the late Richard Roberts, C.E., 

 of Manchester, 1840. 



2069. Parallel Motion. 



The Committee, Royal Museum, Peel Park, Salford. 



Consisting of one wheel revolving within another of double its size, and 

 carrying a pin whose centre, coinciding with the pitch line of the lesser wheel, 

 traverses a straight line equal to the diameter of the larger. [The invention 

 of the late Mr. James White, of Manchester.] 1842. 



