Scientific Industries. 477 



tage of the facilities-for serious study offered by the various evening 

 schools in the district. The happy relations existing between the 

 firm and their employees have no doubt largely conduced to the 

 well-being and prosperity of the company. 



J. & E. HALL, LTD., DARTFORD IRON WORKS. 



These works, established in 1875, furnish an example of a large 

 engineering concern in this district which has developed a field of 

 industry of its own by creating designs of refrigerating machinery 

 on a system of universal applicability, and used on land and sea in 

 all parts of the world. To keep pace with the demand, it has been 

 necessary to develop and modernise the works in recent years. 

 Now they cover several acres of ground well situated near river and 

 railway, and capable of a large output. 



The original firm was founded by John Hall, carried on at his 

 death in 1836 by his two sons John and Edward, and in 1900 turned 

 into a limited liability company. In addition to the engineering 

 works, the founder acquired gunpowder mills at Faversham, paper 

 mills at Horton Kirby, and other manufacturing concerns. A 

 world-wide reputation was acquired by him for papermaking and 

 gunpowder machinery. Up till recently the manufacture of gun- 

 powder machinery was continued as a speciality, complete plants 

 being installed in all parts of the world. He did much to develop 

 the beam engine and " elephant " boilers in the early days of steam. 



Richard Trevithick was engaged at these works, and amongst 

 other things brought out what was very probably the first steam 

 turbine engine. 



The first trunk engines ever made were designed and constructed 

 at these works for the s.s. " Dartford," in 1835. 



It was not till 1878 that the works became connected with 

 refrigeration for the elimination of heat, when the Giffard Cold Dry 

 Air Machine was brought over from the Paris Exhibition of 1877, 

 and for some years the firm devoted their attention to the fitting 

 up of ships for the carriage of foreign meat on this system. 



The most common method now of refrigeration is to cause some 

 liquid to pass to the gaseous state, thus producing cold, and the 

 agents chiefly used are ammonia, carbon dioxide, sulphur 

 dioxide, and ether. The selection of the refrigerating agent 

 is one presenting some difficulties, and this firm adopted carbon 

 dioxide as the most suitable, it being non-poisonous, non- 

 corrosive on metals, cheap, and having an efficiency fully as great 

 as any of the other agents. The carbon dioxide apparatus was brought 



