258 DR. LOUIS VESSOT KING ON THE PROPAGATION OF SOUND IN THE FREE 
some reason to believe that a large proportion of the atmospheric losses take place in the immediate 
vicinity of the fog signal station. It is of considerable importance that the characteristics of the wave- 
motion be studied in some detail in this region. The results of the acoustic survey just described may 
be regarded as giving us some preliminary information of conditions to be met with in the design of 
apparatus especially suited to determining the wave-form and numerical characteristics of waves of 
large amplitude. 
No. 2 .—Short Range Acoustic Survey. September 4 and 5. Table 2 and Chart 2. 
The phonometer observations, entered in Table 2 and shown graphically in Chart 2, were taken from a 
ship’s boat (Plate (ii.)). The position of the boat was determined at each signal by measuring the angles 
between known landmarks by means of a sextant. The observations extended over two days, September 4 
Observations carried out from a ship’s boat by means of the Webster phonometer. The position of the 
ship’s boat at each signal (identified by means of the numbers on the chart) was obtained from sextant 
observations. The phonometer readings at each position are plotted along ordinates at right angles 
to the inward and outward courses. Wind directions and velocities (represented by arrows) are 
those registered at the meteorological station. 
and 5, 1913. Fortunately, wind and weather conditions did not differ greatly on the two occasions. 
In order to obtain some idea of the relative amounts of sound propagated over sea and land, the 
observations of September 2 are graphically represented in Chart 2 on the same scale. Attention is drawn 
to the fluctuating character of the gradients along lines I. and VIII. In both instances we have examples 
