1 87 ij Scientific Inventions, 563 



iron ore, and a new Gyrometric Governor for steam-engines. Instead of the 

 controlling pendulum hitherto employed, Mr. Siemens substitutes a parabolic 

 cup dipping into water, and rotating about a vertical axis. Above the cup, the 

 top and bottom of which are both open, are several vanes : the water, as the 

 cup revolves, rises in the interior with the increase of rate, and, if the friction 

 thus produced is not sufficient, overflows against the vanes, enforcing uniform 

 velocity by a differential motion acting on the throttle valve of the engine. 



Sir Joseph Whitworth contributes a measuring machine, a modification of 

 that which obtained the Council Medal in 1851, capable of being read to the 

 one-millionth of an inch. The principle is that of employing the sense of 

 touch to aid that of sight, the gauge being made to pass between two perfectly 

 true parallel planes, until the movement of the micrometer brings the surfaces 

 so close that it is possible to feel the contact. This mode of delicate measure- 

 ment follows from Sir Joseph Whitworth's invention of the method of 

 obtaining a true plane surface. 



Mr. J. Warsop exhibits an Aero-Steam Engine, showing the application of 

 the well-known fact that all water holds air in solution, and which acting as 

 an elastic spring between the molecules of water, promotes ebullition. On 

 this principle Mr. Warsop introduces, from an air-pump worked by the engine, 

 a current of heated air into the water contained in the boiler. The air is 

 heated by being forced through pipes placed in the flue or the smoke-box, thus 

 utilising what has hitherto been waste heat. The airis passed into the water 

 from a long perforated tube extending the whole length of the boiler, so that 

 by the force of impact the whole body of water is constantly stirred and 

 aerated. This agitation prevents the deposit of saline matter. Thus there is 

 both a saving of fuel and a prevention of incrustation. 



Messrs. Cooke and Sons exhibit a fine achromatic equatorial telescope 

 (7435), of 10 inches aperture and 124 feet focal length, with a clock in which 

 there are arranged two separate trains of wheels driven by the same weight. 

 One train is in gearing with a revolving fly, and also moves the telescope. 

 The other drives an ordinary clock pendulum ; this train having one wheel 

 attached to an arm swung from a pivot on the frame, and shifting to the right 

 or left with the pendulum. By this means the exact measurement due to a 

 pendulum clock is obtained without any unevenness of movement. 



Messrs. Elliott Brothers exhibit several new instruments. The Omnimeter, 

 for surveying, consists of a theodolite telescope with a powerful vernier 

 microscope. The telescope is pointed successively to two lines upon a staff 

 of known length, and the arc described by the telescope gives the distance of 

 the staff. The Planimeter, for estimating as accurately as possible the area 

 of plans, resembles a large pair of compasses with a revolving disc at the 

 joint of the legs, one of which is fixed, the other traced over the plan to be 

 measured. The area is read off the disc, according to any scale to which the 

 instrument has been set. Messrs. Elliott also exhibit Mr. Richards's steam 

 indicator, which has been successfully employed in recording the variation in 

 pressure of engines running at the highest speed. 



Captain Le Boulenge contributes a chronograph for measuring very minute 

 intervals of times. Two cylindrical bars, held up by electro-magnets, are 

 allowed to fall freely in parallel vertical lines close together. One bar is of 

 some length, and is sheathed with a covering of zinc ; the other is short and 

 drops upon a table almost as soon as released. In doing so, the blow struck 

 upon the table liberates a knife, which indents a mark on the soft metal of the 

 long falling bar. If the chronograph be applied to the measurement of the 

 velocity of projectiles, the latter bar is set free when the bullet pierces the first 

 screen, and the shorter bar when the bullet cuts the target. The distance 

 through which the bar has fallen of course readily gives the time of the 

 passage of the bullet. 



Mr. T. E. Rowe exhibits a model of a Relume Signal Lamp, or a lamp 

 which shall re-light itself automatically. It is well known that a compound 

 straight bar will become bent by the action of heat, and will straighten itself 

 again on cooling. Such a compound bar is fixed above the flame of the lamp, 

 and a catch fixed to the end of the bar is held in place while the lamp is 



VOL. VIII. (O.S.) — VOL. I. (N.S.) 4 D 



