310 
ANNALS NEW YORK ACADEMY OF SCIENCES 
Papers. 
Charles G. Cook, The Relation of Modern Theories of Matter to 
the Teaching of Physical Science. 
Frank B. Spalding, Apparent Location of Objects under Water. 
R. W. Sutliffe, A New Construction of the D’Arsonval Type 
Measuring Instrument. 
D. W. Hering, The Distortion and Oscillation of Helical 
Springs. 
William Campbell, Simple Experiments in Matallography for School 
Work. 
Summary of Papers. 
Professor Hering presented a continuation of an earlier paper on helical 
springs. In this he discussed the effect which the mass of the spring has on 
the period of oscillation. It was shown that this effect is the same as would 
be due to the suspension of a mass whose moment of inertia with reference 
to the fixed end of the spring is equal to the moment of inertia of the spring 
itself about the same point, and comparisons were made between periods 
determined from this theory and those actually observed. 
Professor Campbell described the simple apparatus necessary to prepare 
and examine metals and alloys under the microscope. For elementary work, 
wrought iron, mild steel, rail steel, tool steel and white and gray cast iron 
could be examined using the material worked with in the forge, foundry 
and machine shop. Then a few simple alloys such as lead solders or hard 
lead (antimony lead alloys) could be prepared and finally a brass and a 
bronze examined. The whole work outlined was to explain the properties 
of the material used in the shop-work. 
The Section then adjourned. 
William Campbell, 
Secretary. 
BUSINESS MEETING. 
October 4, 1909. 
The Academy met at 8:28 p. m. at the American Museum of Natural 
History, President Cox presiding. 
The minutes of the meeting of May 5 were read and approved. 
