ILLUSTRATING ITALIAN SCIENCE. 893 



3. Hydrometrical pendulum of Venturoli, constructed by the engineer 



Albanesi, of Venice, in 1790. 



4. Model of the Cremona regulator for dispensing water. 



5. Model of the Piedmontese regulator for dispensing water. 



6. Model of the regulator of the Milanese Bocca Magistrate for dispensing 



water. 



7. Eall plummet, 30 metres long, with small brass chain for centimetres 



and millimetres (1860). 



8. Pilot tube, modified by Mallet, length 14 metres, with float, constructed 



by the Koyal Observatory of Padua (1852). 



9. Tachymeter, of Briinnings, constructed in the workshop of the Koyal 



Observatory of Padua, in 1483. 



10. Portable hydrometer, in several pieces, length 8 metres, of recent con- 



struction, to take the surface of the water of rivers with perfect 

 accuracy, whence to deduce the declivity of the superficies, and to 

 introduce it into the hydraulic formulae ; constructed in the workshop 

 of the Royal Observatory in 1874. The cabinet has three of them, 

 which admirably answer the purpose. 



11. Retrometrical rod, of Teodoro Bonati, of wood, composed of 10 pieces, 



constructed at the Royal Observatory of Padua in 1848. 



12. Small mill by Woltmann, constructed in the workshop of the Royal 



Observatory of Padua in 1858. 



13. Float, simple and compound. 



14. Retrometricat Asta, of Teodoro Bonati, composed of tin tubes, 16 

 metres long, divisible into 38 pieces of various lengths, constructed in 1859. 



? 15. Pilot Tube, modified by Darcy, constructed by Sarran of Paris, in 

 1871. 



16. Small mill of Woltmann, constructed in 1870, by J. Kern of Aaran, 

 with two flyers and two wheels unequal in size. 



17. Tachymeter of Briinnings, modified by Professor Turazza, constructed 

 in the workshop of the Royal Observatory of Padua, in 1859. 



4563. Photographs of Scientific Instruments in the 



Cabinet of Physical Science, Royal University of Padua. 



Director, Prof. Rossetti. 

 (1.) INSTRUMENTS OF GALILEO. 



a. Apparatus to demonstrate the theorem that a body falls in 

 equal time from a chord and from the vertical diameter of a 

 circle. 



b. Telescope. 



c. Atmospheric and water thermometer. 



d. Natural loadstone, armed, weighs 2J oz., supports 100 oz. 

 The scale is about mill. 100 to a metre. 



(2.) INSTRUMENT for dividing by Musschenbroeck, improved 

 by Poleni, 1740-1760. 



(3.) INSTRUMENT by s'Gravesande for central force ; improved 

 by Poleni, 1740-1760. 



(4.) CONDENSING ELECTROMETERS, by Prof. Salvatore Dal 

 Negro, 1804. 



These instruments are interesting, historically ; upon the results obtained 

 by them, Dal Negro disputed the theory of Volta, and established from the 



