A YEAB IN SCIENCE 35 



the side opposite the 10, 20, 30 (degrees), etc., markings 

 of the centigrade thermometer, fill in the corresponding 

 numbers of the Fahrenheit thermometer. Find the 

 value of one degree centigrade in terms of Fahrenheit 

 degrees. Find the value of one degree Fahrenheit in 

 terms of the centigrade degree. 



Problems: 1. Fifteen degrees C. are equal to how 

 many degrees F. ? 



2. Forty-five degrees F. are equal to how many 

 decrees C. ? 



3. The centigrade thermometer registers 21 degrees. 

 What does the Fahrenheit thermometer register at 

 the same time? 



4. The Fahrenheit thermometer registers 14 de- 

 grees. What does the centigrade thermometer 

 register at the same time? 



5. What is the principle upon which the construc- 

 tion of the thermometer is based? 



Exercise 14. Measurement of the Heat of a Flame. 



It is a well-known fact that if any substance is held 

 in a flame, its temperature is increased. The cause of 

 this increase is called heat. To measure this increase 

 sonic unit of measure is necessary. To this unit the 

 name gram-calorie has been given. A gram-calorie is 

 lh< (unounf of heal, necessary to raise one gram of water 

 <>< degree ccnliyrade-. 



Object: To determine the amount of heat given off 

 by a given flame in one minute. 



