42 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 
star’s brightness was 14400 times 240 ft.-lbs. — 3456000 ft.-lbs. 
of energy. 
For a body in motion, the established relation between its 
weight expressed in pounds, its energy in foot-pounds and its 
velocity in feet per second is W = 64 1-3 ye So the weight 
Aza 3456000 il 
of our shooting star was 64 1-3 —— == )hb.= > 
(26 X 5280) 84 5) 
Not infrequently a meteor weighing many pounds reaches the 
earth’s surface—as claimed for the black stone enshrined in the 
Kaaba at Mecea. But the usual shooting star which is dissi- 
pated in the air, is a light body—in many instances not more 
than a grain in weight. 
OZ. 
Causes of Sudden Brightness and Quick Extinction 
When a moving body is checked, or stopped, its seemingly 
lost energy instantly reappears as heat. 
The simple clapping of hands—repeated checking of motion 
—heats them. A piece of iron on an anvil hammered sufficient- 
ly, becomes red hot. Visitors to the Chicago exposition in 1893 
recall the muscular Samoan who, astride a dry log, so vigor- 
ously, rubbed the end of a stout stick back and forth along a 
shallow groove in the log that soon it was ablaze! 
Mechanical energy checked, is converted into heat at the rate 
of 772 ft-lbs. of energy to one heat unit. The heat which raises 
the temperature of a pound of water one degree Fahrenheit is 
taken as a unit of heat. 
The air’s resistance checked and soon stopped our shooting 
star’s swift motion, converting its astonishing amount of en- 
ergy, 3456000 ft.-lbs., into a correspondingly large quantity of 
heat, 4477 units. This much heat would make a half-gallon of 
ice-cold water boil—and boil away as steam! Its self-evolved 
heat raised the substance of the shooting star to incandescence 
—caused its sudden brightness. Did it melt and vaporize the 
matter of the ttle meteor? Let us see. Had its weight been 
84 times greater—a full pound—and its substance solid plat- 
inum, one of the most refractory of metals, it would have been 
melted by only 49 units of heat—provided the temperature was 
as high as 3230 degrees Fahrenheit. 
Experiment shows that when a body speeds through air 125 
feet per second its temperature rises 1 degree. If its velocity 
is doubled, its temperature rises + degrees; if trebled, 9 degrees. 
