Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

381 OF ENGINEERING FORMULÆ. Light. Velocity of light 192,000 miles per second, nearly. Decomposition of Light. Violet = maximum chemical ray. Indigo. Blue. Green. Yellow = maximum light ray. Orange. Red = maximum heat ray. Primary. Red. Yellow. Blue. Combinations of Colour. Secondary. Orange. Purple. Green, Tertiary. Brown. Grey. Broken green. Contrasts of Colour. Primary Colours. Secondary in contrast to Primary. Tertiary in contrast to Secondary. Red. Yellow. Blue. Gieen. Purple. Orange. Brown. Grey. Broken green. Sound. Velocity of sound in air................. „ water ............. wet sand .. . ■ • • ” contorted rock .. .. ” ” discontinuous granite ” " solid granite........ " „ iron .. __............ „ copper .. •. • • • • o wood .................. • Distant sounds may be heard on a still day. Human voice __________ ....................... Rifle _______________________________ Military band •• *...................__ Cannon ............................... __________ = 1,142 feet per second. = 4,900 „ = 825 „ = 1,090 „ = 1,306 „ = 1,664 „ = 17,000 „ = 10 378 „ = 11,000 „ (pine) to 16,700 „ (aspen) 150 yards. 5,300 „ 0,200 „ 35,000 „ _______________________