74 EFFECTS OF WINDS AND OF 



solution. These were based mainly upon evidence which indicated that 

 when there was an apparent shift of the wind direction between the direc- 

 tions N and NE or between the directions S and SW the water surface at 

 Cleveland in frequent cases did not respond in the normal manner. There 

 were two surmises as to the reason, one connected with the possible be- 

 havior of the water itself and one a suspicion as to the wind record. 



Plate 2 shows that with a shift of the wind from N to NE or from S to 

 SW there is a very large shift in the position of the nodal line on Lake Erie. 

 This means that for a slight change in direction of the wind, only 45, there 

 must be a transfer of an unusually large amount of water over an unusually 

 long distance before the new steady regime is established. Accordingly, at 

 the time of said shifts it is possible that there are decidedly unusual tem- 

 porary fluctuations in elevations of water surface at various points due to 

 inertia effects in the unusual currents which must occur at those times. Cleve- 

 land, lying between the two locations of the nodal line for S and for SW 

 winds, may be especially subject to such temporary fluctuations of elevation 

 of water surface. 



The other surmise arose from two considerations : 



First, in talking with officials of the Weather Bureau in both Chicago and 

 Washington the idea was several times advanced that at particular stations 

 there might be errors in the recorded direction of the wind at the station, 

 due to the immediate surroundings of the station, such that the recorded 

 wind direction of the station might not be truly representative of the wind 

 direction in a large region around the station. For example, it is possible 

 that for certain hours a wind may be recorded as NE at the Weather Bureau 

 station at Cleveland though the actual wind blowing at that time over the 

 western half of Lake Erie and influencing the water surface might be a north 

 wind rather than a northeast wind. 



Second, for certain days in which there seemed to be reason to suspect the 

 validity of the Cleveland wind directions in the respect just noted, a com- 

 parison was made of the wind directions recorded at Cleveland and those 

 recorded at Buffalo and other stations. These comparisons in some cases 

 indicated fickle fluctuations of wind between N and NE as recorded at Cleve- 

 land when the record at other stations showed no reason to apprehend such 

 fluctuations. It was therefore surmised that possibly there might be a tend- 

 ency to station error in the wind direction at Cleveland, affecting especially 

 the directions N, NE, S, and SW. This is the only case in this investigation 

 in which there appears to be any reason to suspect an appreciable station 

 error in either wind direction or wind velocity. 



The total number of rejections and combinations made on the unusual 

 basis indicated above was moderate. Table No. 12 shows that the total 

 number of rejections in solution W29 at Cleveland was only 7 per cent and 

 the total of combinations was only 6 per cent, whereas the corresponding 

 percentages for all four solutions combined were 4 and 5, respectively. 



The external evidence seemed to be ample and convincing that all these 



