Heale. — On Moon Occultations. 61 



I have hei'e the computations of five occultations -which I have observed 

 with a portable telescope at different times without any special care. Of these 

 four agree with one another within a maximum of seven seconds ; the fifth is 

 apparently affected by some blunder, as it varies upwards of twenty seconds 

 from the others, but, as even this discrepancy is only about four and a-half 

 statute miles, it might be considered accurate in comparison with the 

 approximations generally available on board ship. 



The calculation of longitude from the observations is, it will be observed, 

 not by any means formidable for its length, and it presents no intricacies 

 which an ordinary navigator may not easily master. 



