66 ANNUAL OF SCIENTIFIC DISCOVERY. 



or any similar mechanical indicator of level or perpendicularity. This 

 level, by always maintaining its position with reference to the horizon 

 or line of true level, affords a means of measuring vertical angles, just 

 as the magnetic needle serves to measure horizontal angles. The mo- 

 tions of this level, as the carriage passes over irregular surfaces of 

 ground, are communicated to the carriages of the friction face-wheels, 

 and consequently regulate their velocities. Thus a given number of 

 revolutions of the wheels of the carriage moves the paper farther, and 

 of course the pencil draws a longer line, when on level ground than 

 \vhen either on ascending or descending ground. The locality of any 

 particular points is marked at the time of passing them upon the line 

 thus drawn, by simply pulling a lever, which marks upon the paper a 

 line across the base-line or line of distance. The distance of any two 

 of these points can readily be determined by dividers and a scale of 

 equal parts. Another pencil is mounted so as to traverse in a line at 

 right angles to the direction in which the paper moves. When this 

 pencil is held stationary it draws a line upon the paper parallel with 

 that drawn by the other, representing level ground ; and it represents 

 rising ground when it recedes from the other pencil, and falling ground 

 when it approaches it. The steeper the elevation of the ground, the 

 greater must be the velocity with which it approaches or recedes from 

 the other pencil. The several movements of this pencil, backward 

 and forward, are produced by means of friction face-wheels, differential 

 screws, &c., deriving their motion from the wheels of the carriage, 

 and modified, as in the first case, by the level or pendulum. There 

 are many conveniences combined in the instrument, such as scales 

 of distance and the numbers of the stations printed upon the paper 

 by the mechanism itself; signal bells, to give notice of the approach 

 to a station, &c. The engineer can, at a glance, in any part of the 

 survey, tell the distance he has come, and the difference of level of any 

 points in the survey. Messrs. Sellers and Whetstone, of Cincinnati, 

 are the inventors. 



INTEGRATING ANEMOMETER. 



A SHEET of plain paper, placed in the instrument, under a register- 

 ing pencil, is moved forward by rotating, hemispherical fans, at the 

 rate of one inch for every ten miles of air that passes ; this same pen- 

 cil, having a lateral motion given to it by a vane, records the point of 

 the compass from which the wind blows, and a clock-hammer, de- 

 scending every hour, strikes its mark on the margin of the paper, to 

 express the time. Thus, in a single line, are given the length of the 

 current, its direction, and the time occupied in passing a given sta- 

 tion. London Athen&um, Aug. 



NEW METHOD OF CONSTRUCTING GATES AND DOORS. 



A MR. SHEPARD has invented a new method of constructing gates 

 and doors. Instead of hanging them in the usual way, by hinges, or 

 running them on wheels, he suspends them to iron bars extending 



