SCIENCE— ADVERTISEMENTS 



THIS new form of Demonstration Balance enables the most accurate verification of the princi- 

 ples of moments. The adjustments permit of varying the conditions in the greatest number 

 of ways. The center of gravity may be changed so as to be either below, on the level with, 

 or above the knife edge. The knife edge itself is a very delicate construction and is made by allow- 

 ing two very hard steel points to rest in two V shaped grooves. The counterweight on the pointer 

 permits of adjusting its weight. The plumb bobs on the scale pans and support permit of accurately 

 leveling this apparatus and make it possible to make the forces act in the exact perpendicular to the 

 length of the level arm. The scale and a clamp which holds the knife edge are both adjustable 

 and the entire instrument is mounted on a tripod base with leveling screws. Nickel plated through- 

 out, making a very handsome appearance. 



W. M. WELCH SCIENTIFIC COMPANY 



Manufacturers, Importers and Exporters of Scientific Apparatus 

 1516 Orleans Street CHICAGO, ILL., U. S. A. 



