248 



Measurement of Time. 



Nil. .M 71 



51727. 1:5. 



51 728 B. 1:5. 



51 728 A. 1 : 5. 



Secondary Clock (sympathetic clock), in wood case with carved frame and shielding glass 

 for protected rooms. 



List No. 51,718 51,719 51,720 51,721 51,722 51 723 51,724 

 Diam. of dial cm 21 24 31 40 50 64 74 



Price 3. 0. 3. 5. 4. 0. 5. 0. 7. 10. 10. 0. 11. 10 



The dials have a white ground and black figures, also black pointers; other patterns can be sup- 

 plied at a proportionate increase in cost. The clocks are also supplied with carved frame at a corre- 

 sponding extra cost. If with double dial these clocks cost up to 31 cm diameter double, and the 

 larger ones 75 to 40% more. 



Prices for secondary clocks in metal cases for unprotected rooms and for the open quoted on 

 application. 



51.725. Metronome (Malzl's) with Bell, Figure, striking the 2 nd , 3 rd 4 th and 6 th beats loud 

 51,725 a. - - i d e m, without bell 



51.726. - - idem, with bell and Electric Contact, Figure, for releasing the fall machine 

 and marking the closing of the circuit by striking a bell 



51.727. Metronome with clockwork and mercurial contact, for Beckmann's experiments, Figure 



51.728. Chronoscope (Hipp's), Figures A and B 



This is a most accurately working instrument for determining small intervals of time. It is 

 employed in the determination of the frequency of sounds, the velocity of free-falling bodies, the 

 velocity of flight of shots, etc. The instrument indicates accurately to 0.001 second. The arrestment 

 is released a\itomatically by means of two draw cords or electrically by the aid of a double relay fitted 

 to the back. 



51,720. Current Circuit Fall Trough (Kolbe's) 



A ball traversing a fall channel closes an electric circuit during a certain duration of time. 

 depending on the inclination of the channel. 



51,730. Spark Chronograph (Tuning Fork Chronograph), as suggested by v. Beetz, F i g u r e 



(Fogg. Ann., Vol. 135, 1868, p. 126) ' 



A tuning fork of 250 vibrations, fixed to an axis of rotation, and sliding along a prism, writes 

 with its style upon a lacquered and sooted surface. By discharging an induction apparatus, the sparks 

 of which pass between the point of the style ami the soot -covered 

 The determination of time is accurate to within 0.0005 second. 



s. .1. 



surface, time marks will be given. 



"iI.T.'.l. Cylinder Chronograph, with Hipp Eegulator, Figure, length of a second 10 mm; 

 time (it observation up to 00 minutes. 



Price, without precision clock or chronometer 



The paper-covered cylinder is actuated by a weight-driven clockwork having a Hipp regulator. 



0. 15. 

 0.12.0 



1.10.0 



1. 5.0 



20. 0.0 



7. Id. (I 



85. 0. 



wo, 



MO 



