OF ARTS AND SCIENCES. 



319 



" It is quite probable, that the conical and pyramidal earthen and 

 brick chimney-tops now and for many years so generally used are 

 modifications of those introduced or recommended by Cisalpin, Saint- 

 Martin, and Tredgold. 



Time in Velocity per 

 Seconds. Second. 



31.0 



31.0 

 31.5 



Fig. 10. 



''^ExpAQ. Cone, with its cap, made according to 

 the proportions laid down by Saint-Martin (see fig. 7), 34.0 



" Exp. 20.* Cone and plate ; inclination of sides to 

 base 45° ; diameter of base 2.9 inches ; height .83 

 inch (see fig. 9), ...... • 33.5 



Feet. 



1.71 



1.71 



1.6S 



31.0 1.71 



" Exp. 14. A truncated cone, diameter of upper 

 surface 1.25 inches; diameter of lower surface 4.3 

 inches; height 1.3 inches; lower surface upon fixed 

 tube ; upper surface in centre of trunk, . 



" Exp. 15. Same cone divided into three cones of 

 equal height by planes parallel to the two surfaces ; 

 two smaller cones, ...... 



" Smallest cone, ...... 



" Exp. 16. Truncated cone, diameter of lower 

 surface 2.1 inches ; height .35 inch ; diameter of flue 

 and upper surface, as usual, 1.25 inches, 



" Inclination of sides to base, in these last cones, 

 the same ; 40°. 



" Exp. 17. Cone ; angle of side 

 with base, at bottom 47°, at top 

 55°, side concave ; diameter of 

 base, 3.7 inches ; height, 1.4 

 inches, ..... 



" Exp. 18. Cone ; angle of side 

 with base, at bottom 44°, at top 



64°, side concave; base 4 inches 



in diameter ; height 1.9 inches, 37.6 1.41 



35.4 1.49 



1.56 



1.58 



* Dimensions of cone and plate, from which this model was made, as fol- 

 low : — diameter of flue 18 inches ; base of cone 3ft. 6in. ; height of cone 12in. ; 

 diameter of plate 3ft. 6in. ; height of plate above top of cone 9in. ; thickness of 

 plate l^in. 



