MECHANICS AND USEFUL ARTS. 



the room he works in, the partial heat of the hands alone being 

 sullicient to render it useless for its object. In getting up straight 

 edges and llat surfaces, if two only are used to test eaeh other, it is 

 all but a certainty that one will be hollow and the other rounding, 



^2 



but by using three we are enabled to discover this delect." 



MACHINERY vs. MAN-POWER. 



Mr. T. A. Mclntyre, of Albany, communicates to the Scientific 

 American the following notice of some rapid work which recently 

 came under his observation in a planing mill of that city, lie says: 

 ** The proprietors received orders one morning to tongue and groove 

 4,000 boards. The demand being urgent, they put their machines 

 to their highest speed. Noticing the remarkable speed with which 

 the boards went through one of the machines, 1 thought I would 

 time it, and found that 1 ( J boards passed through in two minutes, 

 this would be 570 in an hour, and 6,270 in a day (11 hours being the 

 mill day). A man at a liberal estimate, could not put in a tongue 

 and groove and plane more than four boards an hour ; so that this 

 machine, with one man feeding and two men taking away, did as 

 much work as 142 men. 1 ' 



STEEL SHIPS. 



"Two large ships, built of steel plates, were recently launched in 

 the Mersey. Though some small vessels have been built of the same 

 material, this is the first instance in which steel has been used for 

 ocean ships. The steel now manufactured for shipbuilding purposes 

 is said to have an advantage over iron, in being more ductile and 

 malleable, as well as stronger and lighter. These qualities bring 

 with them, it is also said, greater economy in building and increased 

 capacity, both most important considerations. Mr. Jones, one of 

 the builders, states that in the Formby, one of the newly launched 

 vessels, of 1,276 tons burden, the weight of steel used is 500 tons, 

 whereas, if she had been constructed of iron, 800 tons of that metal 

 would have been required. In a vessel like the Warrior, he declared 

 that by using steel greater strength might be obtained with a saving 

 of one half in the weight of metal. Mr. Reed, constructor of the 

 Navy, made a special journey from London to attend the launch and 

 examine the ships. He remarked, that merchant ships can be built 

 to test a principle, when war ships cannot, as the former can be ex- 

 amined and repaired annually, while the latter are sent abroad for 

 periods of three or four years. He perfectly agreed with what had 

 been said of the importance of steel for the construction of small 

 ships, and stated that the Government took great interest in the ques- 

 tion of employing steel as a material for ship-building." Journal of 

 the Society of Arts. 



ENGINES WITHOUT BED-PLATES. 



On the engines of the two great iron-clad vessels constructed dur- 

 ing the past year by (.'apt. Ericsson, the Puritan and I)icia1or, there 

 is a novelty which warrants attention. They have neither bed-plates 

 nor frames, properly speaking. The duty borne by these details 

 usually found in other engines, is transferred to light but rigid 



