6 PREFACE. 



no particular region is mentioned, the occultation will be visible at 

 Washington. 



In order to render this list available, as far as possible, to all who take 

 an interest in phenomena of this nature, I have given so much of Professor 

 Bessel's method of predicting occultations as may be necessary for deter- 

 mining, from the quantities T, H, etc., all the particulars required for the 

 purpose of maldng an observation, with an example of its practical appli- 

 cation. 



The second list has been prepared with particular reference to the 

 NatioTial Observatory at Washington. The mean solar and sidereal times of 

 the immersions and emersions, with the angular positions on the moon's 

 border of the points of contact of all stars to the seventh magnitude inclu- 

 sive, which will be favourably occulted, have been computed as they will be 

 seen at that place. In the few instances where occultations which take 

 place below the horizon are given, the times of immersion and emersion 

 may serve the purposes of observation at places not far distant from 

 Washington. 



JOHN DOWNES. 



Philadelphia, October, 1850. 



