170 Experiments J or delerminirig the [M.irch, 



As to his works, he has left but few behind hitn. Nor shall we 

 be surprised at this, if we consider the country in which he spent 

 his life, the difficulties with which he had to struggle in the early 

 part of his career, and the arduous contest which, during a period 

 of 12 years, drew the whole attention of the Americans to politics, 

 and which left behind it such a deterioration of moral character, 

 such a state of agitation and discontent, as must long prevent any 

 great advancement of the sciences in that boisterous and unsettled 

 republic. Mr. Rittenhouse left behind him 22 papers, all printed 

 in the four volumes of the American Philosophical Society's Trans- 

 actions, which have been already published. These papers are 

 chiefly astronomical ; and the most important of them all is the 

 account of the transit of Venus in 17^9, printed in the first 

 volume, and drawn up by Dr. Smith. 



Article IF. 



Experiments for determining the Draught of Carriages, uilh and 

 without Springs. Extracted from an Essaij on the Construrtio?i 

 of Roads and Carriages. By R. L. Edgeworth, Esq. F. R. S. 

 M.R. 1. A. and Civil Engineer. 



Theory shows that whilst the wheels of a carriage pass over an 

 obstacle the load on the carriage must rise along with the wheels, 

 unless it is supported by springs ; but that if the load is hung upon 

 springs, whilst the carriage-wheels tend to throw the load upwards, 

 as they rise suddenly over an obstacle, the springs will bend, 

 because they are opposed, not only by the weight, but by the vis 

 inertice of the load acting downwards ; and the load will conse- 

 quently not be thrown up snddenly so high, as if there were no 

 springs ; for the weight cannot he thrown upwards instantly ; it 

 requires a certain time to throw any weight upwards through a 

 given space, and it is well known that in all cases this time must be 

 equal to that In which a body would fall through the same space. 

 So that making allowance for the imperfection of springs, it is easy 

 to calculate their utility in lessening the draught of a carriage over 

 an obstacle, if the height of the obstacle, the velocity of the car- 

 riaee, the height of its wheels, and ot the load which rests on 

 springs, be known. 



Upon sul»)ects of this sort, which are of such universJil concern, 

 the best possible proofs should be given of the truth of "whatever is 

 proposed for general adoption, particularly where popular prejudice 

 is directly in opposition fo what is advanced. Let the accuracy of 

 models, and their resemblance to realitij, be ever so great, the 

 mind still requires what is rt-a). The ploughman will not be con- 

 vinced by experiments made on the models of ploughs, nor the 



