1078 SEC. 20. MISCELLANEOUS. 



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. Retroinetrical 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. Retrometrical Asta, of Teodoro Bonati, composed of tin tubes, 16 

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



15. Pitot 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 

 first the foundations of the chemical theory of the pile. {See Description of 

 a new electrometer and some experiments in charging the voltaic column, 

 by Ab. Dal Negro, T. X. I., Italian Society of Science, Modena, 1804.) 



(5.) 1 and 2. OLIGOCHRONOMETER, by Prof. Salvatore Dal Negro, 

 applied to researches on the laws of weights falling freely. By 

 cutting the thread which holds the weights suspended, the 

 pendulum is set at liberty, which, being stopped by the weight 

 arriving at the end of its course, cuts another thread. 



3. Oligochronometer. (See New method for measuring the 

 smallest fractions of time, invented by the Ab. Dal Negro, Padova, 

 1816. New Oligochronometer, Padova, 1809.) 



(6.) MODEL OF OLIGOCRONOMETEK, by Dal Negro, applied to 

 the measurement of the velocity of projectiles. 1 . Cannon, the ball 



