PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 379 



two stationaiy entwines are used, opposite eacli other, for tlie purpose of 

 g-iviiic: motion to tlie iron wire ropes to wiiicli iire attached a gang of plows 

 attended by one man. They often cut totiiedeptli of eig-liteen inches. The 

 grounil there is, generally speaking, heavier than ours, and being clayey 

 is more dillioult to [)low. It is found that, by using tlui stationary engine, 

 between eight and nine bushels more of grain can be raised per acre. This 

 n)ore than pays I'or the plowing by steam 



These stationary engines are arranged to be moved from -one (ield to 

 another. Tliey are owned by companies of large capital devoted to this 

 business alone. The price asked for plowing an acre is five English shil- 

 lings. There is one company which charges as high as fifteen shillings. 

 This plowing is done when the soil is in such bondition tliat it could not be 

 accomplished by horses. The deep cut, which turns up soil not before 

 brought into use, is the cause of the increased crop. The cost of these sta- 

 tionary engines is from six hundred and fifty to fifteen hundred pounds; 

 they are of about fovty-five horse power. Mr. Lee did not wish to be under- 

 stood as condemning the locomotive plow which was now presented in 

 model. He was in favor of locomotion by steam wh(>never it can be made 

 practicable. 



New Method of Strengthening Cast Iron. 



Mr. A. L. Floury presented specimens of iron made by the patented pro- 

 cess of Mr. Win. M. .\rnold, of this city, and remarked that the increase of 

 strength in cast iron, is of great importance, and the invention of Mr. 

 Arnold deserves our full attention. He has succeeded after many years of 

 experiment, in obtaining the valuable alloy, samples of which are now 

 shown. It has been tested at the Wiard Ordnance works Trenton, at the 

 West Point Foundry and at the Morgan Iron Works. Acording to the cer- 

 tificate of Mr. P. P. Parrott of West Point Foundry, the tensile strength 

 of one bar was 19,248 lbs., per square inch, and of another 15,443 lbs. — 

 According to experiments made at Trenton and at the Brooklyn Navy Yard, 

 the strength of ordinar}' Scotch Pig Iron was increased about one hundred 

 per cent. l)y Mr. Arnold's process. , 



The strengthening of iron so as to reduce the weight or quantity required 

 in the construction of locomotive carwheels, rail road machinery, bridges 

 and ships, involves the question of safety as well as economy. All machine 

 builders and workers in iron appreciate the importance of increasing the 

 toughness of the principal material used by them. 



The texture of the improved iron is uniform throughout the mass, and 

 very different from ordinary cast iron, which is generally coarser grained 

 and weaker near its centre. Another interesting feature of Mr. Arnold's" 

 iron, is that acids and salts have little action upon it. The metal receives 

 a high polish and can be drilled and worked into anj' shape with facility. 



The process of preparing the iron is very simple. It consists in adding 

 a certain proportion of melted copper, zinc and tin to the iron, when in the 

 liquid state and as it ie poured into the mould. The arrangement of the 

 flask for this purpose, constitutes one part of Mr. Arnold's invention. He 

 states that the cost of strengthening iron according to his plan will not 

 cost over fifty dollars per ton. 



