of the Total Eclipse of July 28, 1851 . 16^ 



central line is 189". The longitudinal line passing through 

 "Vladimir, if traced to the bottom of the map^ is found to 

 correspond to the factor 7. Hence the duration of total 

 darkness at Vladimir will be 189" x 0-7 = 132". 



Opposite Vladimir, the angles from the sun's upper point 

 at disappearance and reappearance are respectively 64° and 

 116°. The longitudinal line passing through Vladimir, if 

 traced to the top of the map, is found to correspond to the 

 correction 46° towards S. Hence the angles from the sun's 

 upper point for disappearance and reappearance at Vladimir 

 will be 



64° + 46°= 110° and 116° + 46°= 162. 



Addendum to the ^'Suggestions to Astronomers for the Observation 

 of the Total Eclipse of the iSmw." 



It is recommended that a careful examination of the sun's 

 disc be made, for the discovery ^of conspicuous faculae or 

 maculae, in the neighbourhood of the limb. Before the 

 eclipse, the examination should be made round the whole 

 circumference : after the eclipse, those parts should be par- 

 ticularly examined near which red prominences may have 

 been seen. 



Meteorological and Astronomical Notices. By Professor 

 C. PiAZZi Smyth. Communicated by the Author. 



The appropriate principle for Anemometers at Sea, — In our 

 last notice much stress was laid on the importance of observ- 

 ing the wind more carefully at sea, by using instruments on 

 Edge worth's hollow-hemisphere principle, and by taking into 

 account the correction for the motion of the vessel. That 

 the necessity of the latter should ever have been doubted by 

 scientific men seems strange, when all of them must have 

 heard of Bradley's having been led, 100 years ago, to the 

 discovery of the aberration of light, by observing the apparent 

 change in the direction of the wind, as his boat sailed up and 

 down the river ; and being further informed by the sailors, 

 on remarking the circumstance to them, •* that it was always 

 so ;" viz., that the change of the direction of the boat's motion 



