Page:Narrative of a Voyage around the World - 1843.djvu/34

 xxviii deep in the rock on which it is based to furnish specimens for future analysis. You will of course keep a register of the contents of the auger every time it is withdrawn, and if the structure or density of the coral appear to change, it will be desirable to have a series of such specimens also preserved, and tallied with their corresponding depths.

Immediately that the bore hole arrives at its greatest depth, provided no water has been allowed to enter, it will be well to contrive some method of sending down a registering thermometer, so as to ascertain the temperature of the bottom of the hole.

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 nine, and its two minima of three 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 providing authentic data, from all parts of the world, for the use of future labourers in meteorology, whenever some powerful mind should happily rescue that science from its present neglected state. But those hours of entry interfere so much with the employments of such officers as are capable of registering those instruments with the precision and delicacy which alone can render these data useful, that I do not think these journals should be further required. The daily height of the former, and the extremes of the thermometer, will be sufficient to record, unless from some unforeseen cause you should be long detained in any one port; a system of these observations might then be advantageously undertaken.