888 SEC. 20. COLLECTION OF APPARATUS AND PHOTOGRAPHS 



of the second. (B.) Instruments to measure the variations of the horizontal 

 component and of the inclination. 



6. Differential interrupter, made by Prof. Blaserna, for the study of 

 currents induced and of the extra currents. Full description given in the 

 " Giornale di Scienze Naturali ed Economiche," Palermo, 1870. Sensitive 

 from T-rnrWn to l " 



._ lOO'OOO . 



ectric and magnetic apparatus, for measurement and by projection: 

 (A.) Quadrant galvanometer, by Dr. Carl, for instruction purposes, with two 

 threads, one thick and short, the other fine and long. (B.) Sine and tangent 

 compasses. (C.) Apparatus of projection, by Prof. Blaserna, for the demon- 

 stration of magnetic phenomena, provided with two arresters of the oscilla- 

 tions, one by water and the other of thick brass, for experiments in deviation 

 and oscillation, (D.) Electrometer (Thomson), according to Kirchhoff, for 

 projection. (E.) Wiedemann's compass, with three pairs of spirals by Kipp. 



8. Electric apparatus, for measurement and by projection : (A.) Bifilar 

 electrometer of Palmieri, made by De Palma, of Naples. (B.) Edelmann's 

 compass. (C.) Thomson's galvanometer. (D.) Wheatstone's rheostat. 



9. Electric apparatus, for measurement and by projection : Wheatstone's 

 bridge, made by Stohrer, of Leipsic, with its commutator, Kipp's rheostat. (B.) 

 Astatic galvanometer, with a very short thread, to show the thermo-electric 

 currents, and currents of terrestrial induction by projection, made by 

 Campbell. (C.) Astatic galvanometer, with a long thread and reflector, made 

 by Ruhmkorff. (D.) Electric multiplier, by Belli. 



10. (A.) Perfected Kipp's chronoscope, with apparatus for the fall of 

 weights. (B.) Kipp's chronograph. 



4557. Drawings of Scientific Instruments in the Univer- 

 sity of Turin. Director , Dr. Angela Mossi. 



1. Physiological apparatus, for measuring the movements of the blood- 

 vessels : 



A. Pletismograph, and apparatus for producing artificial circulation in 



organs separated from the body. 



B. Pletismograph, to note the movements of the blood-vessels in man. 



(See two printed descriptions attached.) 



4558. Photograph of a Dielectrical Machine, system of 

 Prof. Cecchi. Prof. Filippo Cecchi, Florence. 



4559. Photograph of an Electric Motor, on the plan of 

 Prof. Cecchi, of Florence. Two rectilineal electro-magnets with 

 polar masses of iron are alternately magnetised, and by means of 

 levers and eccentrics produce the motion. 



Prof. Filippo Cecdii, Florence. 



The electro-magnetic motor of Prof. Cecchi, of Florence, is set in move- 

 ment by two rectilineal and parallel electro-magnets placed horizontally upon 

 a wooden base. Each of these electro-magnets bears at one end a mass of 

 soft iron, while from the other projects a metal point, which by means of 

 a small band moves a long lever of the third order, and this last moves by 

 means of another very long band an eccentric, situated on the axis of 

 revolution. OH this same axis there is also a commutator which serves 

 to send a current of electricity alternately into one and the other of the 

 electro-magnets. This motor, on equal conditions, has a force superior to 

 that of many other electro-magnetic motors. 



