80 Barometrical Measurement of the 



which is estimated by Captain Horsburg at 7400 feet, and \fre/ 

 had reason to conclude, from the angle which it subtended at 

 diflPerent distances, justly estimated. The summit of Fuegir waS 

 Visible from the ship for two days, rising much above the clouds, 

 and always clear ; no smoke proceeded from it, although it is 

 said to be generally burning. I cannot conceive a station 

 more eligible for interesting experiments, connected with the 

 relations of heat add moisture to the atmosphere. 



I take this occasion to bring under your notice an inaccurate 

 practice which prevails in our directories, and even in works 

 of higher authority, of stating the geographical position of a 

 bay, anchorage, or town, generally, instead of specifying some 

 particular bearing in the anchorage, or spot on the shore. 

 Madeira affords an instance which is quite in point. It iS re- 

 corded in the directories that Captain Flinders found Funchal 

 Bay in 16° 55' 24" W. longitude, and Captain Heywood in 

 16*^51'; I believe that it is just possible that a difference of 

 longitude equal to the disagreement, may be comprised within 

 the limit of the bay, or nearly so, although it is more probable 

 that a considerable portion of it at least is due to an actual 

 difference between the captains, than to the distance apart of 

 their respective anchorages. The present notice of the direc- 

 tories may be sufficient to enable ships to find Funchal Bay ; 

 but it does not supply a means of comparing chronometers with 

 correct Greenwich time, which is so important to navigators, 

 especially at a port frequently touched at by ships bound on 

 distant voyages. The usual passage from the ports of the 

 Channel to Madeira is from seven to ten days, an uncertainty 

 therefore amounting to two miles in the part of the bay for 

 which the longitude is assigned, and which is well within the 

 limit of the anchorage, makes a corresponding doubt in the 

 time of eight seconds, or nearly a second a day in the ra!te 

 of the chronometer ; an uncertainty which is of great mag- 

 nitude, when it is remembered that whatever error it oc- 

 casions, is multiplied in the subsequent voyage by as many 

 times as the number of days between England and Madeira are 

 repeated. It would be very desirable that the geographical 



