1 58 CALORIFIC POWER Of FUELS. 



The cards are shown in Fig. 40, reduced in size, the actual 

 lines and spaces being as follows: 



FlG. 40. RlNGELMANN SMOKE SCALE. 



Card o, all white. 



Card i, black lines I mm. thick, 10 mm. apart between 

 centres, leaving spaces 9 mm. square. 



Card 2, lines 2.3 mm. thick; spaces 7.7 mm. sq. 

 Card 3, lines 3.7 mm. thick; spaces 6.3 mm. sq. 

 Card 4, lines 5.5 mm. thick; spaces 4.5 mm. sq. 

 Card 5, all black. 



