Second R'.port of the British Association. 131 



and falls by jerks, and much too irregularly for this plan to be adopted with 

 safety, at least in our river. 



" Mr. Palmer has described, in the Philosophical Transactions, a self- 

 registering machine which is intended to give the time and height of high- 

 water; and I believe it is intended to set one up at the London Docks, but 

 I have not heard that it is yet in operation. The principle consists in a style, 

 or pencil, which is moved horizontally by the tide along the summit of a 

 cylinder, which is turned round slowly and uniformly ; the pencil describes 

 a curve upon paper wound round the cylinder, which curve indicates the 

 fluctuations of the water. The motion of the tide being originally vertical, 

 is changed by a common mechanical contrivance of the simplest kind. 



" When it is intended to make a long series of observations, it is of course 

 very desirable to adopt every precaution to ensure accuracy ; but many per- 

 sons have it in their power to make observations, which may be useful in 

 determining the establishment of a port, or the mean interval between the 

 moon's southing and the time of high water, without any expensive appa- 

 ratus. 



" For this purpose the observations during one lunation, or even leas, 

 may suffice, where, as in the river Thames, the rise is considerable and the 

 tides little subject to irregularities. In the open ocean, where the rise on 

 the contrary is small, the tide often hangs half an hour at high water, and 

 the phaenomena take place very irregularly. At St. Helena the rise in 

 springs, according to Dr. Maskelyne, is 39 inches, and in neaps 20 inches ; 

 and I apprehend that less information could be elicited from a year's obser- 

 vations there, than from a month's observations at the London Docks. When 

 a few observations only are made with a view of determining the establish- 

 ment, they should not be used to determine that quantity absolutely, but 

 they should be compared with observations at some place of which the esta- 

 blishment is accurately known, or where observations are continually car- 

 ried on. It would be very desirable for those who are able, to combine so 

 as to effect the monography or detailed description of the tides through some 

 short extent of coast, such as that which has been effected by M. Daussy for 

 the coast of Fiance." 



Some observations on the progress of the tide-wave around the 

 globe, and on the cotidal lines which represent the successive posi- 

 tions of its crest, conclude the Report. Our readers are already 

 aware of the value of the contributions to the planetary theory, 

 the theory of the moon, and other portions of Physical Astrono- 

 my, which have accrued from Mr. Lubbock's application of his 

 powerful analytical talents to those subjects. We hope we may in- 

 fer from the following passage near the end of this Report, that the 

 theory of the tides will ere long receive an equal degree of improve- 

 ment from the same source: — " The analytical investigation of the 

 motions produced by changes of temperature, and of the propaga- 

 tion of heat in fluids, is one of extreme difficulty, and has not yet 

 been attempted. In order to approach this important question with 

 any chance of success, it seems necessary to consider the problem 

 in the first instance in its most simple form, and one in which the re- 

 sults of theory can easily be compared with those of observation." 



We have next to notice a " Report upon the Recent Progress and 

 Present State of Meteorology " by James D. Forbes, Esq, F.R.S. 

 L. & E. &c, since elected Professor of Natural Philosophy in the 

 University of Edinburgh, in the room of the late Sir John Leslie. 

 This Report cannot fail to be highly advantageous in directing the 



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