MECHANICS AND USEFUL ARTS- 43 



hour, so that any number of messages may be sent or received from 

 the exchange- in 17 seconds." 



IMP MOVED RAILWAY CAR TRUCKS. 



In car trucks, as generally constructed, the wheels arc made fast to 

 the axles. It follows that they must be of equal size, and pass over 

 tracks of equal length at the same time, or there must be a sliding or 

 jumping motion given to one of them equal to the difference in the 

 size of the wheels, or the length of the track. But practically, the 

 wheels cannot be made or kept of the same size while in use, nor can 

 the tracks on the right and left of the cars be of the same length, ex- 

 cept while running in a straight line ; the consequence must be that, a 

 grinding, sliding, and jumping motion is nearly constant. The result 

 of these irregularities and inequalities is to rapidly destroy both the 

 wheels, axles, and rails; also, to weaken the cars. 



An estimate of the amount of this sliding and jumping, which occurs 

 every day on extensive roads, will astonish every one who has not in- 

 vestigated the subject. Suppose the wheels upon the opposite ends of 

 the axle in a rigid truck differ in their circumference the amount of 

 one-fourth of an inch. At every revolution the lesser wheel must be 

 brought up to equal the larger by a jump or slide. This difficulty is 

 rather increased in passing curves. These objections attending the use 

 of a " rigid truck " are sought to be overcome by Mr. Walter Youmans, 

 Lausingburg, N. Y., in an invention, the fundamental principles of 

 which are comprised in making the wheels turn on adjustable axles, and 

 in so adjusting the axles as to keep them always at right angles to the 

 truck. By this improvement it is claimed, that all sliding and jumping 

 of the wheels is obviated ; for turning independently of each other, 

 each wheel is kept in its proper position, without causing any strain 

 upon its fellow. 



A considerable gain in the power of the locomotive is obtained, by 

 being relieved of the necessity of turning every axle in the train with 

 every revolution of the wheels, at a leverage of about 16 inches from 

 the centre of motion. This improvement seems to have great merit, 

 and will doubtless find its wav into universal use. 



/ 



Railway Car for different Gauges. The following is an invention 

 of Mr. Tisdale, of Boston, by means of which a car can be made to 

 conform to two different gauges of railway tracks. The wheels are 

 made to move upon the axle back and forwards by flanges, running be- 

 tween two rails placed on each side of the truck, so forming a groove, one 

 end of which is set to four feet eight and one-half inch gauge, the other 

 to five feet six inch ; by moving the car back or forwards in the groove , 

 the wheels open or close together on the axle ; when they have come to 

 the desired gauge they are fixed firmly and very simply by clutch boxes 

 and wedges, which turn round by hand and lock Avith a slide key. 

 When this is done the car is ready for use. 



IKON MASTS. 



The Achilles, one of the new iron-dads of the British Navy, has 

 been fitted with iron masts. Of these the mainmast weighs no less 

 than 21 tuns 12 cwt. ; its length being 121 feet !) inches, diameter 

 three feet four niches, and length of head from hounds 2U feet. Each 



