i8o 



Yacht Curves. A set of curves for boat or yacht designing. [13, 



* 15, 21, 24, 27.] 



Yeast-Testing Apparatus. Apparatus for estimating the amount 



of CO 2 evolved from yeast. 

 Y-Level. A surveyor's level with Y-supports for the telescope, 



enabling the latter to be reversed. [2, 6, 9, 13, 15, 16, 17, 



21, 24, 25, 26, 27.] 

 Young's Modulus Apparatus. For the determination of Young's 



modulus of elasticity. See also Searle's Apparatus. [4, 19.] 



Zenometer. An instrument for measuring the angle of depression 

 from a ship's bridge, and getting the distance of a buoy or 

 other object. Can be fitted to any sextant. [15] 



Zoetrope. An optical toy, also known as the " Wheel of Life." 

 A circular series of pictures representing moving figures, 

 etc., in successive phases is placed vertically in a revolving 

 cylinder and viewed through narrow slots cut in the cir- 

 cumference of the cylinder. A life-like appearance of motion 

 is apparent to the observer. The germ of the modern 

 cinematograph. 



Zollner Spectroscope. See Spectroscope. [2, 13, 14, 26.] 



Zoogyriscope. A form of kinematograph or animatograph. 



Zoophyte Trough. A small glass trough used for examining 

 small aquatic objects under the microscope. [2, 3, 20, 22, 

 26] 



Zoopraxinoscope. An instrument similar to and the same as a 

 phenakistoscope, by means of which pictures projected upon 

 a screen are made to exhibit the natural movements of 

 animals and birds. 



Zymoismeter. An instrument for ascertaining the degree of 

 fermentation occasioned by the mixture of different liquids 

 and the degree of heat which they acquire in the process of 

 fermentation. 



