INTRODUCTION. XIX 



CLASSIFICATION OF THE COLLECTION. 



Arithmetic. 



Apparatus for teaching arithmetic. Calculating machines. 

 Instruments for solving equations. Slide rules. Numbering and 

 enumerating apparatus, &c. 



Geometry. 



Instruments used in geometrical drawing. Methods of copying 

 Pantigraph, micrograph. Peaucellier's cell and parallel motion 

 Machines for description of curves and specimens of the curves 

 they describe, including geometric turning. Instruments for giving 

 graphic representations of phenomena. Models to illustrate de- 

 scriptive geometry. Specimens to illustrate the process of making 

 models according to a design. Models to illustrate solid geometry, 

 perspective, crystallography, &c. Stereoscopic illustrations of 

 solid geometry. 



Measurement. 



Of length. Standard yard, metre, &c. Comparator for stand- 

 ards of length (sight and touch). Gauges, measuring wheels, 

 steel tapes, &c. Micrometers and verniers. Cathetometers. 



Of area. Planimeters, &c. 



Of volume. Standard gallon, litre, &c. Pipettes, burettes. 

 Meters for gas, water, &c. 



Of angles. Divided circles, theodolites, clinometers, gonio- 

 meters, &c. 



Of mass. Standard pound, kilogramme, &c. Vacuum and 

 other balances. 



Of density. Specific gravity bottles, areometers, &c. 



Of time. Clocks and pendulums, chronometers, watches, and 

 balance wheels. Tuning forks for measuring small intervals of 

 time. Chronographs. 



Of velocity. Such as Morin's machine. Strophometers, cur- 

 rent meters, ships' logs, &c. 



Of momentum. Ballistic apparatus. 



Of force. Spring balances, pressure gauges, torsion balances, 

 &c. 



Of work. Indicators, dynamometers, &c. 



Kinematics, Statics, and Dynamics. 



Elementary illustrations. Position and displacement of a point, 

 a rigid body, or a material system. Composition and resolution of 

 displacements. Velocity and acceleration, their composition and 



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