Xexo IVeigfUs and Measures. H? 



j6 only the resistance of the air (increasing as the square of 

 the velocity) that prevents this indefinite acceleration and ulti- 

 mately renders the motion uniform. 



Secondly. Setting aside, again, the resistance of the air (the 

 effects of M liich we shall estimate by and by), the very sa?ne 

 amount of constant force "which impels a car on a rail-way ai 

 2 miles an hour, would impel it at 10 or 20 miles an hour if an 

 extra force were employed at first to overcome the inertia of 

 the car and generate the required velocity. Startling as this 

 proposition may aj^pear, it is an indisputable and necessary 

 consequence of the laws of friction. In fact, assuming that 

 the resistance of the air were withdrawn, if we suppose a 

 horizontal rail-way made round the globe, and the machine 

 (supplied with a power exactly equivalent to the friction) to be 

 placed on the rail-way, and launched by an impulse with any 

 determinate velocity, it would revolve for ever with the velo- 

 city so imparted, and be in truth a sort of secondary planet to 

 our globe. 



Now, it would be at all times easy (as we shall afterwards 

 show) to convert this accelerated motion into a uniform mo- 

 tion of any determinate velocity' ; and from the nature of the 

 resistance, a high velocity would cost almost as little, and be 

 as easily obtained as a low one. For all velocities, therefore, 

 above fom* or five miles an hour, rail-ways will afford facilities 

 for communication prodigiously superior to canals or arms of 

 the sea. — Scotsman, Dec. 8, 1824-. 



WEIGHTS AND MEASURES. 

 Copy of a Letter from the Commissioners of Weights and Measures, dated 

 14th January 1825, to J, C. Hcrries, Esq., Secretary of the Treasury, 

 transmitting a Report of the Progress made in the preparation of the 

 Models of the new Weights and Measures. 



London, January 14, 1825. 

 Sir — I am directed by the Commissioners of Weights and 

 Measures to transmit to you, for the information of the Lords 

 Conmiissioncrs of His Majesty's Treasury, the inclosed Report 

 from Capt. Kater, stating the progress which he has made in 

 the preparation of the models of the new weights and mea- 

 sures, in ))ursuance of the directions contained in your letter 

 of the 13th of .July 1824-, inclosing a copy of a Treasury mi- 

 nute, dated the 29tluof June 1824, respecting the steps neces- 

 sary to be taken for carrying into effect the Act 5th Geo. IV., 

 for ascertaining and establishing uniformity of weights and 

 measures. 



In conse(|ueiice of tlic delay which unfortunately has oc- 

 curred frou) (he difficulties which have been experienced in 



1' 2 the 



