ON TIDAL OBSERVATIONS ON THE HUMBER, 101 
Coefficients of 
Simla (built head West). heeling error, 
Bee COMMNARG Go Dectecie: ithe nab ai one. sa¢ nla’) 0, os bie mouene +2:06 
DOM NREA OVER COMPATION 6 b)ac) oan 4 mms. pieibid 9,0 eumay o.e10 +1:65 
PRPS TCO COTATI a wai os» vyoynp yey ote in fe ayn nin 0 0's + 80 
BPEL (COMIDAEE Shs ctor e chal nnc%r,¢ measiasl anintisinia tin oles + 7 
WOE CORDARE, wale nurs ipl a vb sce oes ba th cheba asm + :70 
Slieve Donard (built head 8.E. to E.). 
Aftermost steering-compass compensated ...+........ + 40 
Second steering-compass compensated .............. + 12 
Skylight-compass compensated .................... + 33 
Poatedaniganay s!. Stow. cay alt. «oko ceed OL + +23 
Portiskylighticompass. 26s lal cca LO + °26 
In other compasses of the ‘Slieve Donard’ the heeling error was almost 
imperceptible. In the case of the ‘ City of Baltimore,’ the large heeling error 
is evidently due to the vertical foree downwards near the stern, erising from 
the ship having been built head north. In the ‘Slieve Donard,’ the small 
heeling error is evidently due to the ship having been built with her head to 
the southward. 
Before leaving the subject of the third Report, we must beg leave to 
mention one point which has made the duty of reviewing the Report more 
difficult than it would otherwise have been, and which we fear will detract 
from its general utility, viz. that the mathematical formule made use of in 
reducing the observations are nowhere given, and that we have been unable, 
im some cases, to verify or use them. We hope that the Admiralty Manual 
may be of some use to future investigators, as providing a uniform notation 
and mode of reduction, which will make the results derived by one investi- 
gator intelligible to all. 
In concluding this notice, we think we may say that the principal deside- 
rata at present are— 
1. That in the construction of iron vessels, regard should be had to the 
providing a proper place for the compass. It is not difficult for any one who 
has’ studied the question to point out arrangements which would greatly 
mitigate the injurious effects of the iron of the ship ; the difficulty is to recon- 
cile them with the requirements of construction and of working the vessel. 
2. That for throwing light on the points which are still obscure, what is 
chiefly required is, that the complete magnetic history of some iron vessels in 
various latitudes should be known. This, we think, might easily be accom- 
plished by observations of deviations and horizontal and vertical force made 
at various fixed positions in an iron vessel in an extended voyage in both 
hemispheres. We need hardly add, that this should be a vessel of war of 
moderate size, and in which the magnetical observations would be made an 
object of importance. 
Report on Tidal Observations on the Humber. Presented by James Oup- 
HAM, C.E.; Joun Scorr Russet, C.E., F.R.S.; J. F. Bareman, 
C.E., F.R.S.; and Tuomas Tuomrson. 
Ar the Meeting of the British Association held at Manchester last year 
a paper was read in Section G, on the Port of Hull, in which occurred the 
