PERIODIC WAVES. 272 
fall gradually decreasing, until the impulse is spent. I have 
mentioned Lake George here only because the effects of gusts of 
wind in producing periodic waves is so very clearly shown in the 
records of the anemometer and lake gauge, that there can be no 
doubt as to the connection between squalls of wind and these 
waves, and the experience gained at Lake George has led me to 
suppose that it is extremely probable that periodic waves are set 
in motion by squalls of wind in Tasman Sea. 
Upon comparing the reported earthquakes with our tide-gauge 
records, I found 10 per cent. of the recorded periodic waves on 
our tide-gauges coincident with earthquakes. We have thus 
accounted for 73; that is, 10 from earthquakes, 62 from waves in 
Bass Straits, and 1 from storm in Tasman Sea—in all 73 per cent. 
of the periodic waves on our tide records—leaving 27 per cent. 
unaccounted for. I feel sure that a more complete knowledge of 
the meteorology of Tasman Sea would account for more than half 
of the 27 per cent. at present unaccounted for. 
No. 14—NOTES ON COMPARISONS OF STEEL AND 
IRON LINEAL STANDARDS FOR - GEODETIC 
PURPOSES. 
By D. M.. Marruanp, LS. 
(Read January 11, 1898.) 
