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“ 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, SaintMartin, and Tredgold.

Time in Velocity per 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,

31.0 1.71 Exp. 15. Same cone divided into three cones of equal height by planes parallel to the two surfaces ; two smaller cones,

31.0 1.71 “ Smallest cone,

31.5 1.68 Exp. 16. Truncated cone, diameter of lower surface 2.1 inches ; height.35 inch ; diameter of Alue and upper surface, as usual, 1.25 inches,

31.0 1.71 “ Inclination of sides to base, in these last cones,

40°. Fig. 10.

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,

35.4 1.49

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Fig. 11.

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,




“ Exp. 19. 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), .




* Dimensions of cone and plate, from which this model was made, as follow :- 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 Idin.

Time in Velocity per Seconds. Second,

Feet. 1.61






Exp. 21.* Cone and plate similar to last; base 2.5 inches in diameter; height.62 inch ; inclination of side to base 45° (see fig. 9), .

33.0 “ Same cone without plate, .

31.0 Exp. 22. Saint-Martin's cone without the cap ; to the upper surface and around the opening a hollow truncated cone is fitted ; height .62 inch ; angle of sides 42° ; larger base of the frustum upward, 24.0

“ Exp. 23. Cone used in Exp. 21, with a hollow truncated cone, .37 inch high, and angle of sides 42°, fitted as in last experiment,

24.5 Exp. 24. Cone; angle of sides with base 48° ; with hollow truncated cone, as in last experiment, 25.0 Exp. 25.

diameter of lower base 2.5 inches ; diameter of upper base 1.6 inches ; height .55 inch ; internal diameter at lower base 1.25 inches, and diverging to 1.6 inches at upper base,

25.5 “ Exp. 26. Cone similar to that used in Exp. 21, with a flat plate, as recommended by Cisalpin (see fig. 6), .7 inch above top of cone; diameter equal to that of base of cone ; on under surface of the plate a hollow cone .37 inch in height, lesser base downwards, 25.0

Exp. 27. Square block representing a chimney ; flue 1 inches in diameter ; sides 2 inches ; height 4 inches; one side towards the blast,

33.5 “ Same, with corner towards the blast,

35.5 “Same, with a small cone .5 inch high ; angle of side 63° ; side to the blast,

37.5 “ Exp. 28. Same block, with its plane upper surface inclined towards the blast, at an angle of 3o with the horizon,



1.57 1.49


37.0 Same, at an angle of 10° with horizon,

39.0 200



1.43 1.36 0.609


* Dimensions of the original of this model : – diameter of Aue 8 inches; diam. eter of cone at base 16 inches; height 4 inches; diameter of plate 16 inches, and 4 inches above top of cone.

Time in Velocity per
Seconds. Second.

Exp. 29. Same block; upper surface horizontal ; a square plate, 2 inches by the side, on that side which is next the blast,

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Exp. 30. Conical tube, open at both extremities; diameter of larger opening 2 inches ; of lesser extremity 1.3 inches; length 4 inches; inclination of sides 5°; centre of lateral opening 1.6 inches from lesser extremity ; lesser extremity turned towards the blast,

35.0 “Same conical tube ; lesser opening reduced to .37 inch,

54.0 Exp. 31. Conical tube, open at both extremities; diameter of larger 3 inches; of lesser 1.25 inches; inclination of sides 15° ; length 7 inches ; centre of lateral opening 1.7 inches from lesser end ; lesser end towards the blast,

28.4 “ Exp. 32. Same conical tube, its sides continued until they form a cone, with its apex turned toward the blast,

51.0 “Same, with its axis making, horizontally, an angle of 35° with the direction of the blast,

31.0 “Same; axis making an angle of 15o with the blast, 30.0



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“ Exp. 33. Conical tube ; angle of sides 47°, open at both extremities; diameter of larger extremity 4 inches, of lesser 1.4 inches ; length 3.3 inches; centre of lateral opening from lesser end 1.1 inches,

“Same tube ; sides prolonged, forming a cone; apex towards the blast,

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Fig. 12,

Fig. 13.



" Exp. 34. Conical tube ;
inclination of sides 90°; larger
end 4 inches, lesser 1.25 ;
height 1.3 inches (fig. 12), 28.5

“ Same ; sides prolonged, forming a cone ; apex to the blast (fig. 13),



Time in Velocity per

Seconds. Second “ Erp. 35. Revolving conical ventilator, accord

Feet. ing to the proportions of the inventor,

. 41.0 1.29

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“In the following experiments on the velocity of currents through the same length of leaden pipe, the current was produced by the same blast acting upon mouth-pieces of different forms and dimensions, applied to the leaden tube and presented fairly to the blast. Fig. 14.

Exp. 36. Elbow, opening turned towards the blast ; current traversed leaden pipe in

19.0 2.706 “Exp. 37. Conical tube, Exp. 30, closed at lesser end, the other turned to the blast,

19.7 2.69 Exp. 33. Conical tube, Exp. 31, closed at lesser end, the other turned to the blast,

13.6 2.85 “ Erp. 39. Conical tube, Exp. 33, closed at lesser end, the other turned towards the blast,

16.0 3.31 Exp. 40. Conical tube, 2 inches long; diame. ter of larger extremity 1.25 inches; diameter of lesser .8 inch, which is presented to the blast,

. 19.7 2.69 Exp. 41. A glass tube, .25 inch bore, and long enough to reach from the centre of the trunk beyond its side, and, consequently, beyond the influence of the blast, was fastened by one of its extremities in a small hole bored for this purpose in the side of the conical tube used in the last experiment, and near its larger extremity. The conical tube was placed in the same position as before. On presenting the flame of a candle or any light substance near the open extremity of the glass tube, a current of air was perceived flowing into the tube.

Exp. 42. Saint-Martin's cone and cap (see fig. 6), with its axis parallel with the blast; blast directly upon the top of the cap,

29.0 1.83 “ Exp. 43. Cone of 45°, with flat plate (fig. 9), axis parallel with the blast, as in preceding experiment, 29.5 1.80

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Time in Velocity per

Seconds. Second. Fig. 15.

Exp. 44. Elbow with its
te mouth towards the blast, and

covered by a flat plate, 3 inches
in diameter and 1 inch from the

Feet. mouth,

27.6 1.92 Fig. 16.

Exp. 45. Same elbow and
t plate, but turned in the opposite

direction with reference to the
blast ; current passed down the

pipe, and traversed it in . 49.0 1.08 “Same elbow, with a curved plate 1.75 inches in diameter, .75 inch from the mouth of the elbow; mouth turned towards the blast,

36.0 1.45 “ Exp. 46. Conical tube, 4 inches long; a plate 3 inches in diameter, and .75 inch distant from lesser extremity, plate turned towards the blast,

38.0 1.40 “ The experiments which follow are on the influence of ventilators upon a current already established, and moving with a certain velocity in the same direction with that produced by the ventilator. The cur. rent is established by placing the farther end of the leaden pipe — that which has heretofore been kept carefully beyond the influence of the blast — in the blast, in such a manner that it shall receive more or less of its force.

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Velocity of established current in seconds,

Elbow with plate; plate towards the blast, .
Cone, fig. 9, without its plate,
Same, with its plate,
Saint-Martin's cone,
Saint-Martin's cone and cap,
Cone; angle of sides 71°; height 1.5 inches,
Conical tube, Exp.31, lesser end to the blast,
Conical tube of 4*, lesser end to the blast,
Conical tube, Exp. 30, lesser end to the blast,
Conical cap; tube of 47°, lesser end closed and


18.2 2.90

turned to the blast, Conical tube ; length 2 inches; diameter at

smaller end 1.25 ; at larger, 2 inches, over which and 1 inch from it is a plate 2.5 inches in diameter, turned to the blast; smaller end

in the leaden pipe, Elbow; plate 1.75 inches in diameter ; .5 inch

from mouth of elbow; plate towards the blast, Same, with plate.75 inch from mouth of elbow, Same; plate 2.5 inches in diameter, 1 inch

from elbow, .

.. 17.0 3.11

20.5 2.58

20.0 2.65 20.75 2.55

17.6 3.00

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