"Exp. 29. Same block; upper surface horizontal; a square plate, 2 inches by the side, on that side which is next the blast, 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, "Same conical tube; lesser opening reduced to .37 inch, "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 1.87 "Exp. 32. Same conical tube, its sides continued until they form a cone, with its apex turned toward the blast, "Same, with its axis making, horizontally, an angle of 35° with the direction of the blast, "Same; axis making an angle of 15° with the blast, 30.0 1.77 "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, 36.5 1.45 32.5 1.63 Exp. 34. Conical tube; inclination of sides 90°; larger end 4 inches, lesser 1.25; height 1.3 inches (fig. 12), 28.5 1.86 "Exp. 35. Revolving conical ventilator, according to the proportions of the inventor, Time in Velocity per Feet. 41.0 1.29 "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. 38. Conical tube, Exp. 31, closed at lesser end, the other turned to the blast, "Exp. 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; diameter of larger extremity 1.25 inches; diameter of lesser .8 inch, which is presented to the blast, "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. 66 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, "Exp. 43. Cone of 45°, with flat plate (fig. 9), axis parallel with the blast, as in preceding experiment, 29.5 1.80 Fig. 15. Fig. 16. Exp. 44. Elbow with its mouth towards the blast, and covered by a flat plate, 3 inches in diameter and 1 inch from the mouth, 66 Exp. 45. Same elbow and plate, but turned in the opposite direction with reference to the blast; current passed down the pipe, and traversed it in. "Same elbow, with a curved plate 1.75 inches in diameter, .75 inch from the mouth of the elbow; mouth turned towards the blast, "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, 36.0 1.45 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 current 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. Elbow with plate; plate towards the blast, Saint-Martin's cone, Cone; angle of sides 71°; height 1.5 inches, 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,. 19.7 2 69 145 3.66 18.3 2.89 25.0 2 12 14.5 3.66 26.0 2.04. "The established current in the following experiments varied somewhat in the different experiments, but was constant during the same experiment; they cannot, therefore, be compared with each other without reference to the velocity of the established current. Saint-Martin's cone and cap, ft. ft. 22.7 2.33 25.5 2.08 22.2 2.39 26.5 2.00 25.5 2.08 27.0 1.96 Model of a chimney; 2 inches by the side; end flat and horizontal; 4 inches long, Model of same dimensions; top bevelled; angle of sides with horizon 40°, Same; angle of plane of top inclined towards the blast, at an angle of 15°, Same; same inclination; .75 inch above top a plate 2.5 inch in diameter,. Same, without the plate; inclined towards the blast 20°, Same, at same inclination; plate .75 inch above the top, Model and inclination same; plate 3 inches in diameter, .75 inch above the top, 23.7 2.27 27.0 1.96 26.0 2.04 18.7 2.83 26.0 2.04 21.5 2.47 26.0 2 04 21.7 2.44 26.0 2.04 21.7 244 26.0 2.04 22.6 234 26.0 2.04 29.6 179 26.0 2.04 25.6 207 26 0 2 04 52.5 1.00 26.0 2.04 42.0 1.26 Conical revolving cap; angle of sides 47°, apex towards the blast, 24.4 2 17 17.8 2.97 Conical cap, fig. 12, 27.5 1.92 18.5 2.86 Similar cone, with opening at apex, 1.25 inches in diameter, fig. 13, . Conical revolving cap; angle of sides 47°; apex to blast, Same, with opening at apex, 1.25 inches in diameter; apex to the blast, 27.2 1.94 21.2 2.50 27.2 1.94 20.0 265 "The current established in the pipe was raised in temperature above that of the impinging current or blast, by placing the pipe in a vessel of hot water. The current in the pipe assumed a temperature of 104°, while that of the blast was 64°. "Elbow with a plate .87 inch from its mouth and turned ft. towards the blast; temperature of current 64°; velocity 2.08 25.5 "Same; temperature of current 104°, "Several other experiments were made, but the results coincided so nearly that they may be considered as identical. "The proportions of those forms of ventilators which the Committee have found most efficient will be placed in the hands of manufacturers." Mr. Bond communicated the results of some recent observations on the planet Jupiter, and on the nebulæ Herschel Nos. 1357 and 1376 and the great nebula of Orion, as follows: "On the 28th of January and 3d of February, we had excellent opportunities for examining both hemispheres of the planet Jupiter, as on both occasions the atmosphere was in a remarkably tranquil state, and the definition good. "On the 28th of January, at 10h 30m. Camb. m. s. t., nine belts were counted, including those covering the polar regions of the planet. The principal equatorial belt was of an even surface, and its edges were nearly parallel. The next north was very irregular, particularly on its northern side. The other belts bore a striking resemblance to cirrus clouds, when about subsiding into the elongated form of cirrostratus. At the same time, the shadows of two of the satellites, the first and third, were seen transiting the disk. The preceding of these shadows when drawing near the limb became less intensely black, and was elongated in a direction nearly parallel to the axis of rotation of Jupiter. The third satellite was seen at the same time on the disk, as a black spot, and was then taken for the shadow of another satellite. It was not until we had compared its place with the ephemeris given in the Nautical Almanac, that we became satisfied that it could not have been a shadow. It agreed, however, with the computed position of the third satellite. Early in the evening, the first and third satellites were observed approaching the primary on the following side. The first appeared to be the smallest. The ingress of the third was observed, and when about half on the disk, it looked like a mountain projection on the limb of Jupiter. Neither of the satellites, when entirely on the disk, was visible at that time. Further observation was interrupted until about the time of ingress of the shadow of the third satellite, the first internal contact of which was noted at 6h 41m 51 sidereal time at the Observatory, the definition being at the time exceedingly fine. We now saw three black spots. The preceding was the shadow of the first satellite, which was now off the disk; the next occupied the position of the third satellite; the last, near the following limb, was the shadow of the third satellite, very black, and larger than the satellite itself in the proportion of 5 to 3. "On the 3d of February, at 9h 30m m. s. t., the opposite hemisphere was presented under equally favorable circumstances. Three belts |
