212 
MR. PALMER’S DESCRIPTION OF 
the house by a light horizontal shaft revolving under the surface of the ground, 
and communicating by bevil wheels with an upright shaft which acts imme- 
diately upon the pencil rack *. 
The references to the details are given on the several Plates. 
Considering how many interests may be affected by the expected change in 
the circumstances of the river Thames, by the removal of London Bridge, it 
appears important that a similar gauge should be established at some point 
above the bridge, so that by the corresponding charts of the two machines, the 
facts will be so clearly exhibited as to defy that contradictory evidence which 
interested persons might hereafter produce, as well as furnish valuable data 
upon which remedial expedients might be founded. 
Since the completion of the machine above described, my attention has been 
directed by Mr. Lubbock to the application of similar means for observing 
accurately the times of high water, not only as a scientific inquiry upon the 
tides generally, but with a view to the construction of accurate tide tables. 
Perceiving the value of that gentleman’s suggestion, I devoted immediate atten- 
tion to the subject, and trust, from the progress I have made, that the object 
will be accomplished in a satisfactory manner. 
To indicate sensibly the time of high water to within any small portion of 
time (such as a minute), required a representation on a much larger scale 
than that above described, and therefore a distinct cylinder became necessary. 
It not being required to register the absolute heights by this machine, I have 
determined on registering only the upper part of the tide, that is, that portion 
which is contained in thirty minutes, of which the highest point will be one. 
Instead of representing the upper part of the tide by a continuous line, it will 
indicate the relative place and the time of it by punctures, one of which will 
be struck in each minute ; so that the real time of any one puncture being 
known, the observer has only to count the number of punctures from that 
whose time is known, to the highest on the scale, and that will denote the 
time sought. 
To accomplish this, the instrument by which the marks are made on the 
paper will not move as the pencil does in the first machine, but, keeping their 
* To avoid derangement of the rate of the clock’s motion, a weight is to be attached to the registrer, 
equal in force to the resistance of the friction of those parts the clock has to move. 
