Stránka:roll 1910.djvu/85

Z thewoodcraft.org
Tato stránka nebyla zkontrolována

BOY SCOUTS OF AMERICA

are in line with the sight object, while B' C is in line with the pegs h c. Then the length of the long base BC^ will equal the dis- tance from B to X. B

C'

V

V 

'A X^^ ^v^ ^v ift. To make a right angle To measure the space between two distant objects, D and E. Line A B on one, then move this right-angled triangle until F G is lined on the other, with B G in line with G H. B G equals the space between D and E then. If the distance is considerable, it may be measured sometimes by sound. Thus, when a gun is fired, a man is chopping, or a dog barking, count the seconds between the sight and the sound of the blow and multiply by 1,100 feet, which is the distance sound travels in a second. Occasionally, the distance of an upright bank, cliff, or build- ing can be measured by the echo. Half the seconds between shout and echo, multiplied by 1,100, gives the distance in feet.