1829 .] 
On the Tides of the River Hugli. 
319 
borate and useless finish given to them. The glass tube has been already describ- 
ed; it is enclosed in a brass one, which equally serves the purpose of a scale, and of 
protection in carriage. Tire nonii, for there are two, move by rack work. The scale is 
of metres and commences at the middle, so that the two readings are + and are 
therefore added together. The nonii subdivide to decimals of a millimetre, one sub- 
division being ,004 inch. The instrument is suspended by a ring affixed to the 
top, and so adjusted as to hang perpendicularly. This instrument is eminently por- 
table, convenient, and accurate; and to evidence the latter point, it may be mention- 
ed, that on comparing this instrument with a very fine Troughton's, the difference 
was found too trifling to deserve consideration. 
But though I highly approve of it, and think it the best I have yet seen, I must be 
allowed to make the following remarks : — 1st, That the outer brass tube which con- 
ceals the greater part of the glass one, is an objectionable arrangement. For, as I 
have before remarked, unlimited confidence cannot be placed in observations made 
with an instrument in which the state of the column cannot be seen in its whole ex- 
tent at the moment of observation. 1 may add, that the above arrangement adds 
to the expense. 
2dly, I object to the rack work, as more expensive and more troublesome than a 
sliding spring clip, and not so accurate. It is greatly inferior to a slow motion 
screw, and I believe fully as expensive. 
3dly, And lastly, I object to a hanging barometer, particularly where, as in the 
syphon barometer, both extremities of the scale are to be read off. The time lost in 
endeavouring to make a correct observation with such a barometer, can only be 
correctly appreciated by those who have themselves made the attempt. So that 
upon the whole, I am inclined to think the arrangement in the plate the least ex- 
ceptionable ; but with regard to the “ fundamental features” of Bunten’s barome- 
ter, i.e. contraction of the tube at the bend, if it be a large one, and the construction 
of ’the principal leg in two parts, with a projecting capillary tube from the 
upper into the lower half, concerning these vital improvements, there can be 
but one opinion. Whether oar English makers will consent to adopt it, or 
if they do, whether they may not charge so high as to render it too expensive a 
delicacy for those who are likely to require it, is a point that must be considered by 
those who are disposed to make trial of, and to order such an instrument. 
II. On the Tides of the River Hugli. With a Plate. 
The attention of the scientific public has recently been directed to the phenomena 
of the tides which prevail in the Hfigli river, by the presentation to the Asiatic So- 
ciety of the analysts of a most elaborate register of daily tides kept for many years.* 
The subject appears highly interesting in its general bearings ; when we reflect 
that the power of this tide has had such influence in determining the formation and 
peculiar appearance of our lower delta; and consider the superior advantages which 
our position at Calcutta appears to enjoy in its navigable facilities, over most parallel 
positions in the embouchures of Hie other great l ivers of the globe. There is then 
little doubt, that anyone who can add to the information already before the public, 
will be excused his presumption, should he venture to intrude with his contribution, 
the result also of his own meditations on the subject. 
I forward for the benefit of your readers, what I think will he considered to con- 
stitute a valuable addition to our information on this subject, viz,, an abstract of a 
tide register kept daily at Mud-point on Sdgur Island, between July 1828f and Ju- 
ly 1829 [PI. V.] It lias not, unfortunately, the advantage of Mr. Kyd’s analysis, of 
being a geueral view ■derived from the observations for many years. It was procured 
by my own private means, and to elucidate some views which 1 have long entertain- 
ed, and which are now confirmed. It remains now to compare this abstract with the 
data furnished by Mr. Kyd’s tables. 
* Published in our last number. It is to be regretted that we could not on that occa- 
sion, from their size and number, give the tables, which are lithographic plates. — E d. 
t The registry commenced on the 10th July 1828, and did not furnish the ex- 
treme tide of the month. The other paths likewise are influenced by this circum- 
stance, especially the centre or mean-path. 
