66 AXXUAL OF SCIENTIFIC DISCOVERY. 



terpreted by reading the letters of one of the sets of alphabets found 

 opposite to the received letters on the other set ; or, in other words, 

 by reversing the sending process. In the machine or apparatus de- 

 vised by the inventor for these purposes, the movable alphabets are 

 printed or written on endless bands or tapes, which pass round rollers, 

 and may be driven by pinions or otherwise. All the pairs of alpha- 

 bets are mounted on an axle, which is caused to rotate by a crank 

 handle or otherwise, so as to bring successive pairs of alphabets into 

 view. London Mechanics' Magazine. 



GREAT TRIAL OF STEAM PLOUGHS. 



An extensive trial of steam ploughs, lasting twelve days, has re- 

 cently been made at Leeds, England, and the Mark-Lane Express 

 gives an elaborate report of the experiments. Most of the work was 

 done by engines stationed at the side of the field, and drawing the 

 ploughs across by long ropes ; though it seems there were at last two 

 engines that travelled over the ground. The Express concludes that 

 the latter system is impracticable, but that ploughing on the long 

 rope plan may be introduced on very heavy clay soils as a par- 

 tial substitute for horses. 



The engines cost from S'2,500 to $4,000 apiece, and the cost of the 

 ploughing ranged from $1.38 to $2.10 per acre. The fastest work was 

 at the rate of about three-fourths of an acre per hour, and the slowest 

 at the rate of an acre in two hours and a half. 



The Express comes to the conclusion that steam cannot be used 

 profitably in ploughing any land that can be ploughed by two horses 

 at the rate of one and one-half acres per day. 



SMOKE FROM GAS LIGHTS. 



It is pretty generally imagined that the smoking of ceilings is occa- 

 sioned by impurity in the gas, whereas, in this .case, there is no con- 

 nection between the deposition of soot and the quality of the gas. 

 The evil arises either from the flame being raised so high that some 

 of its forked points give out smoke, or, more frequently, from a care- 

 less mode of lighting. If, when lighting the lamps, the stop-cock be 

 opened suddenly, and a burst of gas be permitted to escape before .the 

 match be applied to light it, then a strong puff follows the lighting of 

 each burner, and a cloud of black smoke rises to the ceiling. This-, in 

 many houses and shops, is repeated daily, and the inevitable conse- 

 quence is a blackened ceiling. In some well-regulated houses, the 

 glasses are taken off and wiped every day, and before they are put on 

 again the match is applied to the lip of the burner, and the stop-cock 

 cautiously opened, so that no more gas escapes than is sufficient to 

 make a blue flame ; the glasses being then put on quite straight, the 

 stop -cocks are gently turned, until the flames stand at three inches 

 high. When this is done, few chimney-glasses will be broken, and the 

 ceilings will not be blackened for years. 



