17 



that form suggested by the late Dr. Kobinson, and known familiarly 

 as Eobinson's Cups. It consists of four hemisph rical cups or 

 bowls, with their mouth vertical, carried on the arms of a horizontal 

 cross which is fitted to turn on an upright spindle. Such a fan 

 turns only in one direction, and with a velocity estimated to be 

 one-third of the velocity of the wind. About this however there is 

 very great doubt, and whether the register ought to be multiplied 

 by 3, as it now always is, or by some smaller number, such as 2-5, 

 has not been satisfactorily determined. The velocity of the wind 

 can thus not be measured with greater accuracy than the pressure ; 

 and though the papers frequently say with great pretence of 

 exactness, that the mnd had a pressure of so many pounds, or 

 was moving at the rate of so many miles an hour, it must be 

 remembered that these measures are little better than guesses. 

 The whole subject of anemometry is in a most unsettled and 

 unsatisfactory state ; to have a clear idea of how unsatisfactory it 

 is, it is only necessary to read the evidence on" the subject given 

 before the Committee for enquiring into the causes of the Tay 

 Bridge disaster. The attention of the public has been now fortu- 

 nately aroused, and probably some energetic steps will be taken to 

 arrive at a knowledge of the truth. Meantime, those of us who 

 know most about it are perhaps the most painfully conscious of 

 our ignorance. 



TUESDAY, MAY 2nd. 



A lecture on " Aerial Navigation " was given by Frederiok 

 [W. Brearey, Esq., Hon. Sec, Aeronautical Society of Great 

 [Britain. 



In introducing the subject, the Lecturer remarked that he 

 [knew of no branch of science which was more ^worthy of 

 [the attention of Students, than Aeronautics. He then went 

 I on to speak of the interesting information which could be obtained 

 [ from the study of the construction of birds, and from the obser- 

 fvation of their flight. The belief that it is necessary to have, 

 [for aerial locomotion, gas which is lighter than the atmosphere, 

 is'' an error. The resistence of a balloon to progress in the air. 



