LET. X. OF THE LATITUDE AND LONGITUDE. l6l

east of the meridian of London; and this dif-ference, reckoning after the rate of fifteen de-grees to an hour, is 9 minutes and 20 secondsof time. When it is at noon at London, there-fore, it will be 9 minutes and 20 seconds afternoon at Paris ; and on the contrary, when it istwelve o’clock at Paris, it will be only 50 mi-nutes and 40 seconds after eleven at London :so that the clocks at London, ought to be flowerthan those at Paris by 9 minutes and 20 seconds.In like manner, the meridian of New York, inNorth America, being 74 degrees 9 minutesand 45 seconds west of that of London, thedifference of time at those places will be 4 hours,56 minutes, and 39 seconds; so that when it isnoon at London, it is only 3 minutes and 21seconds after seven o’clock in the morning atNew York.

From these circumstances you will readily ob-serve, that as places differ in longitude, or aresituated under different meridians, so the clocksand watches of those places, supposing them tobe well regulated, will shew different hours atthe same moment of absolute time; a differenceof fifteen degrees in longitude, always producinga difference of one hour in the time shewn bythose machines. Knowing, therefore, the dif-ference of time between two clocks, or watches,well regulated, at different places, it will be easyto find the difference of longitude of those places,M by