ON WAVES. 447 
2. 4th Oct., 1836, lat. 55° 32’ N,, long 4° 52’ W. 
Off the Isle of Arran, 50 to 60 fathoms. 
Space 200 feet, time 10sec. = 20: feet per sec. = 13°5 
miles an hour. 
3. 5th Oct. 1836, lat. 55° 29’ N., long. 4° 54! W. 
Of Pladda Lights, 20 to 16 fathoms. 
Space 200 feet, time 11 sec. to 12 sec. = 17°3 feet per 
sec. = 114 miles per hour. 
4. 12th Oct. 1836, lat. 54° 5' N., long. 5° 31! W. 
Off Ardglass Light, in 34 to 40 fathoms. 
Time. 
9°3 sec. 
10:0 
Space = 345 feet< 9:3 = 35 feet — 9 = 174 miles. 
86 
10:0 
5. 12th Oct. 1836, lat. 54° 1’ N., long. 5° 37! W. 
in 53 fathoms. 
9-3 sec. 
Space = 345 feet { 8-6 = 39 feet — 9 = 20 miles per hour. 
8°6 
G6. 12th Oct. 1836, lat, 53° 58! N., long. 5° 39! W. 
in 46 to 44 fathoms. 
Space = 345 feet, time = 9°3 sec. = 37 feet —9 = 19 miles, 
The observations (4-6) were made against a very strong breeze 
and very high waves, about 8 or 9 feet high, and the vessel was 
going in the opposite direction at about the rate of six miles an 
hour. 
7. In 51 fathoms water the City of Glasgow steam packet passed; her waves 
were about 20 inches high, about 12 feet apart, and passed over a space = 150 
feet in 35 sec. = 4°3 feet per sec. 
It became of importance to determine whether the waves of 
the sea produce an agitation which extends to the deep parts of 
the water. It was found that even in moderate depths they do 
not. Thus in a depth of 12 feet—short quick waves, 9 inches high 
and 4 or 5 feet long, do not sensibly affect the water at the bot- 
tom, while waves thirty or forty feet long, oscillating at inter- 
vals of 6 or 8 seconds, produce a sensible effect, although 
much less than at a point nearer the surface. The circumstances 
of these partial oscillations opens up a field of future research. 
The observations made on this subject were obtained by plunging 
a glass tube to a considerable depth, so that the column of water 
contained in it should only be affected by the forces acting upon 
the particles of the fluid at the depth of its orifice below the 
surface. In this way it was ascertained that neither in velocity 
of the wave-surface, nor in the motion of transference of the 
particles, do the waves of the sea resemble the great primary 
wave of translation of the previous experiments. 
It is difficult to ascertain with precision the form of the waves 
of the sea; they appear to belong to the family of the cycloid, 
