XI. TIME. 103 



1. Manometer for steam, air, or water pressure. 



2. Barometer. Counterpoised barometer. 



3. Thermometer. 



4. Tacheometer, or speed indicator. 



5. Balance for light and heavy weights. 



6. Clock with pneumatic motor. 



M. Eugene Bourdon, Paris. 



503. Electric Apparatus by M. Foucault, for keeping up 

 continuously the motion of the clock. 



Conservatoire des Arts et Metiers, Paris. 



509. Marine Chronometer, regulated at sidereal time, used 

 by the Scientific Commission of Noumea in observing the passage 

 of Venus. Messrs. Tondola and Co., .Paris. 



510. Marine Chronometer, suitable for distributing the 

 hour in quarter minutes to an unlimited number of electric 

 receptors, going for one year without being wound up. (System 

 applied for more than three years with complete success.) 



Messrs. Tondola and Co., Paris. 



511. Marine Chronometer, regulated to mean time. Speci- 

 men of ordinary construction. Messrs. Tondola and Co., Paris. 



512. Geographical Clock, with revolving planisphere ; 

 showing the time, longitude, and latitude, of all parts of the globe. 



Messrs. Tondola and Co., Paris. 



513. Astronomical Pendulum Clock. 



W. Blocking, Hamburg. 



514. Wheel-work of Clock. W. Brocking, Hamburg. 



515. Astronomical Pendulum Clock with mercury com- 

 pensation pendulum. Th. Knoblich, Hamburg. 



516. Sympathetic Pendulum. Th. Knoblich, Hamburg. 



517. Chronometer-escapement, n 



518. Anchor-escapement, model. 



Th. Knoblich, Hamburg. 



519. Pendulum Clock belonging to the tide-gauge of Mr. 

 Reitz. Th. Knoblich, Hamburg. 



520. Astronomical Pendulum Clock. 



F. Dencker, Hamburg. 



The compensation pendulum system Jiirgens has an isochronous sus- 

 pension spring, determined by calculation. It is, contrary to the formerly con- 



517. Chronometer-escapement, model. 



Th. Knoblich, Hamburg. 



