MISCELLANEOUS. 1079 



of which on coming out of the mouth breaks a thread which sets 

 the pendulum of the oligochronometer in motion (2). 3. Movable 

 hinged target, which on being hit breaks a thread which stops the 

 pendulum. 4. Details of the oligochronometer. (See New 

 method for measuring the velocity of projectiles, 1824, by Sig. Ab. 

 Dal Negro, Padova, 1824.) 



(7.) 1. ELECTRO-MAGNETIC MOTOR, by Prof. Salvatore Dal 

 Negro. Two permanent magnets suspended like a pendulum 

 can oscillate in the proximity of the poles of a temporary magnet, 

 in which the current circulates alternately in contrary direc- 

 tions, by means of a swinging commutator with small cups of 

 mercury moved by the pendulum itself. The attractions and 

 repulsions which result render the movement of the pendulum 

 continuous, and this, by means of levers, is transformed into 

 continuous rotatory motion. (See Description of electro -magnetic 

 rams (arieti), both simple and compound, by Prof. Ab. Dal Negro. 

 Padova, 1838. Also Annali delle Scienze del Regno Lombardo- 

 Veneto, tomo III. bimestre I., 1838.) 



2. Electro-magnetic Pendulum, by Prof. Dal Negro. The rod 

 of the pendulum is formed by a bundle of permanent magnets, 

 one extremity of which can oscillate between the poles of an 

 electro-magnet. The inversion of the current is effected as in 

 the above-described motor. This pendulum is interesting, his- 

 torically, as recording the first attempts at using electricity as a 

 motive power. 



(8.) ELECTRO-MAGNETIC MOTOR, by Prof. Dal Negro. The 

 apparatus consists of a lever of the first order, to one extremity 

 of which is attached the anchor of an electro-magnet, and to the 

 other a hammer which by alternate elevations and descents strikes 

 a rod. and produces a movement like that of a shuttlecock, and 

 afterwards the lifting of a weight. This movement of the lever 

 produces the inversion of the current in the electro-magnet, and 

 by means of a swing commutator with small cups of mercury. 

 (See Description by Prof. Dal Negro, Padova, 1838, and in 

 Annali delle Scienze del Regno Lombardo-Veneto, tomo VIII. 

 bimestre 1, 1838.) 



(9.) 1. MACHINE for DIVIDING. (Salleron, Paris, 1870.) 



2. Cathetometer of the Tecnomanasio of Milan, improved in the 

 workshop of the Astronomical Observatory at Padua ; added to it 

 is an internal counterpoise. 



3. Balance of precision, by Deleuil, of Paris. 



4. Quadrant Areometer, by Poleastro (1803). It is a hydro- 

 static balance with quadrant. It is used to ascertain the density of 

 fluids, and is much more correct than ordinary areometers. 



5. Spherometer, by Brunner (1870). 



6. Goniometer, by Babinet. 



