PROFESSOR TYNDALL ON THE ATMOSPHERE 
242 
Wind 
Afloat. 
Calm to N.N.W., 5 
Ashore. 
N.W., 2 to 4 
Barometer 
29-5 
Wet bulb 
43° to 40° 
Dry „ 
— 
45° to 42° 
October 31. Partial Summary . — Sea rough, wind and rain. Nearly at right angles to its axis, syren 
exceedingly faint at 3f miles ; no sound of gun or horns. In axis, syren well heard through paddle- and other 
noises up to 2^ miles. In a violent rain-squall, wind force 8, more than 2 miles from station, forcible sound 
heard from syren ; other signals not heard : with less wind, syren heard off end of Admiralty Pier, directly 
to windward ; gun- sounds quenched ; horn-sounds very faint. Atmosphere exceedingly opaque to sound. 
Afloat. Ashore. 
Wind S.W. by S. to W., 4 to 8 W.S.W., 6 to 4 
Barometer 29-6 29-6 
Wet bulb 52° 47° 
Dry „ 54° 50° 
November 1. Partial Summary. — Land- observations by Mr. Douglass. On ramparts of Dover Castle, 
2 miles from South Poreland, wind obliquely against sound, syren distinctly more audible than horn, though 
the latter was pointed towards the castle ; horn feeble ; gun not heard. On the other side, with wind obliquely 
favourable to the sound, at G - 9 miles distance, the syren and horn (the latter now pointed eastward) were 
barely audible ; the gun was not heard. Aerial echoes, 11 seconds in duration, at South Foreland. 
Afloat. Ashore. 
Wind — W.S.W., 5 to 3 
Barometer — 28-9 
Wet bulb — 49° to 46° 
Dry „ — 52° to 50° 
November 21. Partial Summary . — The gun was first fired along the line between the observers and the Fore- 
land, and then at right angles to this line. The report in the former case was sensibly, though not much, 
louder than in the latter. The syren was then blown in the same manner, first with its axis directed upon us, 
and then in the perpendicular direction. The fall of intensity in passing from the one position to the other 
was far more considerable than in the case of the gun. Striking subsidence of sound near the boundary of 
acoustic shadow. Guns fired to leeward produced louder and longer echoes than when fired to windward. 
Afloat. Ashore. 
Wind S.S.W. to W.S.W., 2 to o S.W., 3 
Barometer 29-9, falling 29-5, falling 
Wet bulb 41° to 44° 40° 
Dry „ 44° to 46° . . 42° 
November 22. 
tially the same. 
Partial Summary. — Yesterday’s experiments were repeated and amplified ; result substan- 
Afloat. Ashore. 
Wind W.N.W. to N.W., 7 
Barometer 29-5 
Wet bulb 50° 
Dry ,, 54° 
N.N.W.,7 
29-1, rising 
47° 
51° 
November 24. Partial Summary . — Sound in rear of syren, to leeward, stronger than in front ; stronger also 
at 2\ miles than at 1 mile. A vast augmentation of the sound when syren was turned to leeward. Whistles 
tested : Canadian and 8-inch whistle proved to be the best. The syren, with disks alone, unaided by trumpet, 
proved to be about equal to the best whistles. 
