Hitherto it has been made a part of the duty of all the surveying vessels to keep an exact register of the height of the barometer, at its two maxima of 9, and its two minima of 3 o'clock, as well as that of the thermometer at the above periods, and at its own day and night maximum and minimum, as well as the continual comparative temperature of the sea and air. This was done with the view of assisting to provide authentic data, collected from all parts of the world, and ready for the use of future labourers, whenever some accidental discovery, or the direction of some powerful mind, should happily rescue that science from its present neglected state. But those hours of entry greatly interfere with the employments of such officers as are capable of registering those instruments with the precision and delicacy which alone can render meteorologic data useful, and their future utility is at present so uncertain, that it does not appear necessary that you should do more than record, twice a day, the height of the former, as well as the extremes of the thermometer, unless, from some unforeseen cause, you should be long detained in any one port, when a system of these observations might then be advantageously undertaken. There are, however, some occasional observations, which cannot fail of being extensively useful in future investigations: 1. During the approach of the periodic changes of wind and weather, and then the hygrometer, also, should find a place in the journal. 2. The mean temperature of the sea at the equator, or, perhaps, under a vertical sun. These observations should be repeated whenever the ship is in either of those situations, as well in the Atlantic as in the Pacific; they should be made far away from the influence of the land, and at certain constant depths, suppose fifty and ten fathoms, and at the surface also; and this last ought to be again observed at the corresponding hour of the night. 3. A collection of good observations, systematically continued, for the purpose of connecting the isothermal lines of the globe, and made, as above, at certain uniform depths. 4. Some very interesting facts might result from the comparison of the direct heat of the solar rays in high and low latitudes. The two thermometers for this purpose should be precisely similar in every respect; the ball of the one should be covered with white kerseymere, and of the other with black kerseymere, and they should be suspended far out of the reach of any reflected heat from the ship, and also at the same elevation above the surface of the water; the observations should be made out of sight of land, in a variety of latitudes, and at different hours of the day, and every pains taken to render them all strictly similar and comparative.