The deed of

The Scientific American Trophy, shown on page 447, was donated with the object of fostering the art of aerial navigation. gift by which it was transferred to keeping of the Aero Club of America called for annual competition by heavier-than-air machines, with the understanding that the conditions governing the contest were to be changed from time to time, so as to keep pace with the progress made in the art of flying. On July 4, 1908. Mr. Glenn H. Curtiss won the trophy for that year by flying for a distance of slightly more than a mile in his new bi-plane, the "June Bug." In 1909, Curtiss again won the cup by flying a distance of about 25 miles in a closed circuit. In 1910, Curtiss won the cup for the third and last time in connection with his great flight from Albany to New York, when he covered a straightaway distance from Albany to Poughkeepsie of 744 miles without a stop. Mr. Curtiss by winning three times secured permanent possession of the trophy.

To Convert Degrees Baumé into Specific Gravity. (1) For liquids heavier than water: Subtract the degree of Baumé from 145 and divide into 145. The quotient is the specific gravity.

(2) For liquids lighter than water: Add the degree of Baumé to 130 and divide it into 140. The quotient is the specific gravity.

To Convert Specific Gravity into Degrees Baumé. (1) For liquids heavier than water: Divide the specific gravity into 145 and subtract from 145. The remainder is the degree of Baumé.

(2) For liquids lighter than water: Divide the specific gravity into 140 and subtract 130 from the quotient. The remainder will be the degree of Baumé.

COMPARISON OF DEGREES TWADDELL

AND SPECIFIC GRAVITY.

In order to change degrees Twaddell into specific gravity, multiply by 5, add 1,000 and divide by 1,000.

Example: Change 168 deg. Twaddell into specific gravity.

Sp. gr.=

weight of substance in air

wt. in air+wt. of flask and waterwt. of flask filled with substance and water.

(2) Solids lighter than and insoluble in water. The solid is weighted with a piece of lead and weighed in water.

(weight of substance in air) Sp. gr.(wt. of lead in water)-(wt. of lead

and substance in water)+(wt. of substance in air)

(3) Solids heavier than and soluble in water. Proceed as in 1 a, using instead of water some liquid without action on the solid.

(weight of bulk of liquid equal to substance) = (weight of substance in air) (weight of substance in liquid).

(weight of liquid and bottle)(weight of bottle)

(weight of water and bottle)(weight of bottle)

Tables of Specific Gravity will be found under Weights and Measures.