Life of Count Rumford. 605 



15, 1811,* on his Experiments and Observations on 

 the Advantage of Wheels with Broad Rims for Car- 



D 



riages, etc. He speaks of his trip in the previous 

 autumn in which he had consulted wheelwrights on the 

 subject. He had a carriage constructed for himself on 

 the plan which he advocated, as soon as he returned to 

 Paris, and he braved the ridicule which was sometimes 

 drawn upon him as he drove in it through the streets. He 

 also contrived an instrument, to be attached to the front 

 of his vehicle, for measuring the force required to draw 

 it with three different sets of wheels, and he gives the 

 results of his trial on different kinds of roads, to de- 

 termine the difference of draught as depending either 

 upon the velocity of the motion or the nature of the 

 road. 



On June 24, 1811, he read a paper of his Experi- 

 ments on the Means of perfecting Lamps, and he ex- 

 hibited on the occasion fourteen lamps of his own 

 construction.^ He had read an earlier paper on the 

 subject on March 24, 1806, and made a previous pub- 

 lication upon it in the Philosophical Transactions for 



On February 24, 1812, he brought before his class 

 in the Institute some further inquiries concerning Heat, 

 with a description of his calorimeter. J He said he had 

 been engaged in attempts to devise and construct such 

 an instrument for twenty years, and thought he had at 

 last succeeded. He compares his own experiments with 

 those of Lavoisier. 



Before sessions of his class, on December 30, 1811, 

 and continued September 28 and October 5, 1812, he 



* Bibliotheque Britannique, Vol. XLVII. p. 82, etc. 



f Bibliotheque Britannique, Vol. XLVI1I. 



Bibliotbeque Britannique, Vol. LI., and Nicholson's Journal, June, 1812. 



