VII. HECOHDING INSTRUMENTS. 703 



287 le. Pocket Hygrometer, in maroon case, for travellers. 



L. Casella. 



287 If. Bine's Sensitive Hygrometer, for taking rapid 

 indications of the dew point. L. Casella. 



VII. SELF-RECORDING INSTRUMENTS. 



Barometrograph of Fontana. 



The Royal Institute of " Studii Superiori" Florence. 



Felice Fontana, a native of Roveredo in the Tyrol, was the first director 

 of the Royal Museum of Physical Science and Natural History founded in 

 Florence by the Grand Duke Pietro Leopoldo. Towards the close of last 

 century he constructed several registering meteorological instruments, and 

 among them the present Barometrograph. A float on the surface of the 

 mercury of a large barometer transmits its motion to a section of a cylinder 

 about 70 mm. in diameter, and covered with paper. Every hour an impres- 

 sion is made upon this paper by a steel point set in motion by a clock. The 

 point itself advances a certain distance at each impression, so that its indica- 

 tions end by drawing on the paper, a curve of the barometical oscillations. 



2872. Barometrograph, or Self-Recording Aneroid 

 Barometer. Pillischer. 



The construction of this instrument differs materially from others of a 

 similar nature, by having the entire mechanism placed in a vertical line, 

 whereby friction is reduced to a minimum. 



The aneroid barometer, 18 inches in diameter, has two vacuum chambers; 

 below it is placed the cylinder, carrying a ruled paper coinciding with the 

 scale of the barometer, and driven by a powerful 8-day clock. The pencil 

 point is moved up and down upon a metal rod by the action of the baro- 

 meter, and, by a simple mechanical arrangement connected with the clock, 

 imprints the changes which occur from hour to hour on the ruled paper. 

 Thus a black dotted undulated line is produced, showing the rise and fall of 

 the barometer. 



2873. Self-recording Barometer and Thermometer for 



use on board ships. 



Dr. Franz Paugger, Director of the I. R. Commercial and 

 Nautical Academy, Trieste. 



This apparatus, which is enclosed in a small box, consists of three principal 

 parts : 



A thermometer, a barometer, and a contrivance for registering. 



The thermometer is composed of a system of 10 zinc tubes, one foot 

 (English) in length, placed side by side in the form of a cylinder, each one 

 of which, commencing from the first, transmits, by means of a lever, to the 

 next tube, in a somewhat augmented degree, its linear expansion produced 

 by increase of heat. This system of tubes is suspended in the open air and 

 surrounded by a shell or cover in the form of Venetian, blinds at the back or 

 the parallel tubular box. From the end of the last tube a somewhat longer 

 lever extends jnto the interior of the box, as far as the writing cylinder, by 



