PROCEEDINGS OF THE POLYTECHmC ASSOCIATION. 675 



Mr, Brown said that he had laid wood against a pipe for 12 

 hours, heated at 100 deg,, without being able to set anything on 

 fire, though the wood was charred. He had also applied gun- 

 powder with the same effect. He used precisely the same pipes 

 that Perkins used for his steam generators. We had yet to learn 

 whether carbon is more susceptible of ignition than the wood 

 before it is charred, 



Mr. Johnson. — Charcoal made at a low temperature will ignite 

 at a lower temperature than when made at a high temperature. 

 Perkins' steam generator heated steam to 600 deg, 



Mr. Baker. — A pressure of 70 lbs. will create a temperature of 

 300 deg. I do not believe there has been a single instance of 

 high or low temperature where the steam pipes have caused igni- 

 tion. 



Mr. Johnson. — It should not go out that we have nothing in 

 our buildings which will ignite from steam pipes, when the temp- 

 erature is very high, as from superheated steam. 



Adjourned till Thursday, April 25th, at 7^- o'clock, p. m. 



American Institute, Polytechnic Association, ) 

 April 25t/i, 1861. ] 



Mr. E, L. Pell in the chair. 



sod-seeder and broadcast sowing machine. 



Col. John C. Duane, of Schenectady, N. Y., exhibited and 

 explained a model of a machine with the above title. 



Description of the machi7ie and its operation. 

 The principle upon which the machine depends for its ease of 

 draft, and enables one pair of horses to operate it, consists in 

 having its whole weight, like Fawk's steam plow, balanced upon 

 the broad surface of the roller, which is only heavy enough to 

 crush the clods of earth and prepare the ground for the mower. 

 The cultivator teeth loosen the ground, and by their peculiar 

 curved form, pass over every obstacle. The drag having four 

 rows of teeth, which if placed in line, would be but one inch 

 apart, leaves the ground in the condition of a garden. The roller 

 completes the operation of tilling the earth, and is followed by 

 the plaster machine, which has both a rotary and horizontal 

 movement, which renders it ianpossible to choke. 



