The aegis & intelligencer. [volume] (Bel Air, Md.) 1864-1923, 1890-09-26

An Interesting Outdoor Experiment at oak
land School, Fallston, on the Velocity of
Sound.
For the HgiS and Inteligencer.
1t was found that Mr.. Alphonso Robinson's
residence, from whence two pupils in physical
science attended0 was plainly visible from the
roof and upper pOrches at Oakland, both houses
being located on high ground, at distance from
each other, by the crooked roads, of something
over two miles. Ono dark, still evening the re-
spective parties took their places. At the school
group of pupils on the roof of the front porch,
at an elevation of about 25 feet; at MIR. Robin
sons, Scott Robinson, an enthusiastic hard
working pupil loading heavy fowling piece
with more than the usual quantity of POWDER
but no shot. mounted the corn house, and at
regular intervals, before agreed upon, dis
charged his piece. The flash was plainly visible
at the school, and the report clearly heard
Thomas Pyle, of Pylesvile, who had assisted at
| transits through the winter, held the watch,
never taking his eye off the second hand.
! On the appearance of the flash, Now" was
called by one appointed to that Office, one whose
muscular interval is very small. 1t is gener-
ally known that there is great personal differ,
ence in this respect. While one can say Nov"
BILE loss of time, another will be perceptfble in
terval in getting his vocal organs of"
The report Of the gun signaled itself: On re-
peated trials, the interval between the fash and
the report was found to be evenly seven seconds.
One observation gave fraction less, but for GER
ture of the air was observed and the required
allowance made of LA feet per second, increased
velocity for every degree above 81 degrees. We
locity of sound at the freezing point 1880 feet
The temperature on that evening, 81 degrees.
would give a velocity of 1,124.2. This gave the
distance between the points of observation, 1853
feet.
On pleasant day. not long afterwards the the
odolite taken down to the farm, and the
longest possible base line was staked out from
points from which the buildings at the school
could be seen. The base line was chained three
times with the greatest care. giving u length of
5S2 feet. A point plainly visible through the
telescope. viz, the south west corner of the
chimney at Oakland, was selected, and included
angles taken from the ends of the measured
base. The angle at the east end was S0009> and at
the west end 95o37>, leaving the angle at the apex
4ol4; making air line defiance to the
chimney at the school 7,76S feet. Add to this
the distance beyond base to the point where the
gun was fired. l4O feet, and we have 1908 feet
From this subtract distance from point of OBJ
servation on the porch roof to chimney, 25 feet,
leaving us 1883 feet by trIanRuiation, and 1859
feet by velocity of sound, difference of only IA
feet, showing fairly that with care SOUND may be
used TO measure distance.
NoTE.-As light travels 10000 miles or dis
lance about equal to four times around the earth
in q single second of tune, for ordinary distances
the interval is perfectly inappreciable. Hence
when the flash was seen the sound started on its
journey.