3S 



WELLS'S NATUKAL PHILOSOPHY. 



Explain the 

 construction of 

 the French 

 System of 

 Weights and 

 Measures. 



„ , , To obtain standards of Liquid Measure, ten pounds, or 7,000 



HowaoT7eoD- .„,..„, , •, 



tain Standards grains of distilled water, at the same temperature, are made 



of Liquid ^Q constitute a gallon. The gallon, by division, gives quarts, 



pints, and gills. 



68. The French System of Weights and Measures is 

 constructed on a different plan, and originated in the fol- 

 lowing manner : 



In 1788, the French Government, feeling the necessity of 

 having some standard by which all weights and measures 

 might be compared and made uniform, ordered a scientific in- 

 quiiy to be made ; the result of which was the establishment 

 of the present system of French Weights and Measures, which, 

 from its perfect accuracy and simplicity is superior to all other systems. It is 

 sometimes called the Decimal System, all its divisions bemg made by ten. 



The French standard is based on an invariable dimension of the globe, viz., a 

 fourth part of the earth's meridian, or the fourth part of the largest circle pass- 

 ing through the poles of the earth. 



In Fig. 6, the circle N E S "W repre- 

 sents a meridian of the earth ; and a fourth 

 part of this circle, or the distance N E, con- 

 stitutes the dimension on which the French 

 System is founded. This distance, w-hich 

 was accurately measured, is divided into 

 ten milUon equal parts ; and a single ten 

 million til part adopted as a measure of 

 length, and called a metre. The length of 

 the metre is about 39 English inches. By 

 multiplying or dividing this quantity by ten, 

 the other varieties of weights and measures 

 are obtained. 



69. In the United States, Standards of Weights and 

 Measures, prepared according to the English System hy 

 order of the Government, are to be found at Washington, 

 and at the capital of every State. 



Fig. 6. 



PRACTICAL PROBLEMS ON THE ATTRACTION OF GRAVI- 

 TATION. 



1. Suppose two bodies, one weighing 30 and the other 90 pounds, situated ten miles 

 apart, were free to move toward each other, under the influence of mutual attraction: 

 what space would each pass over before they came in contact ? 



The mutual attraction of any two bodies for each other is proportional to the quantity 

 of matter they contain. 



2. A body upon the surface of the earth weighs one pound, or sixteen ouices: if by 



