236 
PEOFESSOE TYNDALL ON THE ATMOSPHERE 
Afloat. Ashore. 
Wind N.E., 2 — 
Barometer 30-3 — 
Wet bulb — — 
Dry „ — — 
June 2. Partial Summary. — Maximum range of horns to leeward, paddles stopped, about 6 miles. At 3 
miles in the axis E.S.E. all sounds were at first heard, and then became inaudible. At 2 miles in the axis 
three horns sounded together were inaudible. Sound fluctuated in consequence of high wind ; in one instance 
heard out of axis, with paddles going, 3 miles. 
Afloat. Ashore. 
Wind E.N.E., 7 — 
Barometer 30 — 
Wet bulb — - — 
Dry ,, — — 
June 3. Partial Summary . — Maximum range in axis of horn, paddles stopped, over 9 miles; heard with 
paddles going full speed at 3| miles, with wind (force 3) almost opposed to sound. At the maximum distance 
(air still, sea smooth, and sun shining) a single small horn proved equal to two of them sounded together; a 
short wide horn proved slightly superior to a long narrow one. The howitzer, with 3-lb. charge, proved to 
be the best of the guns. 
Afloat. Ashore. 
Wind S.S.W. to E.S.E.N E.N.E., 2 
Barometer .... 29-9 29’6 
Wet bulb — 59° 
Dry „ — 62° 
June 10. Partial Summary . — Maximum range of 3 horns (1 large and 2 small) sounded together 8| miles ; 
might have been heard further. Guns heard also at this distance, but not better than horns. Wind, force 4, 
almost directly across sound, but slightly against it. At 5 miles distance the large horn yielded a serviceable 
sound with paddles going. The whistles proved inferior to two small horns, and the latter inferior to the large 
single horn. Near edge of phonic area whistles better than horns. Between Foreland and Dover Pier sound 
of horns suddenly subsided. Signalled for guns ; they also were unheard. 
Afloat. Ashore. 
Wind S.W. and W.S.W., 5 to 3 — 
Barometer .... — 29-6 
Wet bulb .... — 56° 
Dry „ .... — 58° 
June 11. Partial Summary . — This day was occupied in examining the decay of the sound near the edge 
of the phonic area at both sides of the Foreland. At the pier, and a quarter of a mile from it, no sound heard. 
Wind, force 2, almost dead against sound. On the South Sand Head side decay also very striking, and more 
striking at 2 miles than at 3| miles : wind here, force 2, in favour of sound. The wind unable to atone for 
the acoustic opacity of the day. As before, near edge of phonic area the whistles surpassed the horns. 
Afloat. Ashore. 
Wind S.W. and W.S.W., 2 to 3 — 
Barometer .... 29-7 29-5 
Wet bulb .... — 55° 
Dry „ — 56° 
June 25. Partial Summary . — Maximum range of horns in axis 6| miles. Sounds lost at this distance, but 
again revived to loudness. A second trial caused the sounds to vanish at 6-4 miles ; wind in^ favour of sound. 
The 18-pounder inferior to horns at miles on axis. 
