2/ t 0 Description and Use of the

The use of a warning star is to pointout the true time of the phœnomenon* whichis to be first nearly found by obtaining thetime of the right ascension of that star forthe everting, on Which the observation isintended to be made.

This table of correspondents was formedas follows:

The right ascension and declination ofthe stars was found in round numbers uponthe celestial globe, and written in two co-lumns* inclosing the names of the stars jthe columns for the names of the corre-spondent places being left blank for their in-sertion afterwards :

Next, as the longitude on our new ter-restrial globes is numbered both ways fromthe meridian of London, whatever the rightascension of the signal star may happen tobe, that point of the celestial sphere is like-wise considered to be upon the meridian ofLondon. Therefore,

To gain the longitude in the last columnvf the table, if the given stars were east ofthe signal, the right ascension of the warn-ing star was subtracted from the right as-cension of the given star.

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