log (fig. 4), a. ta. Erail one, which, however, is not as a rule used for speeds over 18 knots. Owing to the increased friction produced by a rotator making approximately goo revolutions per mile, towed at the end of a line varying from 40 fathorns for a 12-knot register on the tafirail to be recorded in the chart room or any other part of the vessel as desired, a chart room electric register has been introduced. By means of an electric installation between the log register aft and the electric register in the chart room, every tenth of a mile indicated by the former is recorded by the latter. Walker's Rocket log (fig. ' Io) is a taffrail one, with V ~. bearings of, '-, N

V ; E D hardened Steeli

= A, , r and is intende

'* “"" " = 17, 12% 2 . iii# " 'L    ' .

A " . » ~, ur - to be slung or fff' 5 ~'f', ,, / | ' ~' ', lf 'r~ i; »~»~W=nr»>l~'»11¥' secured. '=°'» th<=~, "1 Ae* '“ » '% li ft " ai? ” M - f2=*'ff“&211>Ye'1u1w., . fag* -, Jr ' “QR » J r; , 5 ;; u" /~' " the -gllmbal' pat- pg/¢ ~90wA Q 'S 10 X / ', tern as-a6tting /§ , ' 5 *

~¢' A fig for the deck. In W, is .21 ag mo I 20 .6 lg 4' "'“"'~; B taffrail logs, th<»;fvg{f, ill¢ f 80 3, Q 200 mo 'L Y ' »~ g movement ~;yo NA, 455 6 rg?, 1 f - ' the line owing;¥'m~ ' = ' ' 5 l, l j Q; $6 gn', to its '10 PA UNE" 30 s 'gli - 1'fe.~ P” in becomes Spas' fit) K NEPT ¢ 'I if f: ]Y£ i» “ rnod1cand]erk§ '» 60 SHIPLOG 40 y """"“'"'”' ” ' Increasing the ~§ vibration and QQ' 50 'Q 1 ji' I

FIG. 4.-The Cherub Log. ' friction; to ob- ' »»“ viate this a

- .sg . W

speed to 6o fathoms for zo knots, the pull of the line and rotator S0V€1;iH0f d01' EY-Yheil lg is borne by coned rollers, having their outlines tapering to a. iggriolsfiiéeté (gg I?), p T',1 common, point in their rotationfthus giving a broad rolling andtheeyeof the register surface. Strong worms and wheels are substituted for the light M being attached to the ' i 1. clockwork. In fig. 4 the shoe H is secured to the taffrail, and the EOVSFHOIQ Fig- II' fepfe', T V, g rotator in the water is hooked to the eye of the spindle M by the tgtkfe § ;§ 'uf;';f;'; rj, el .5, 4 ' i";> -it hook D. The case A contains the registering wheel work and a with the Cherub log' a , F

sounding bell. The half Small piece of line is in- ' " " it

- .W imbaj B ivotin in the troduced between the F G D' 1 1 t fN t L Ȣ ... gocket Ofp the gage C governor and the eye of- I 7 la P a e O~, Cp une Og V WM D W' " J allows the register to the register. The two principal American taffrail logs are the Negus receive the strainin the

direct line. The bearings

and rollers are lubricated

with castor oil every twelve hours through holes in the sliding case E, and can be examined by unscrewing the case E and the eye M. When not in use, the register is removed from the shoe by lifting a small screw button neat C. The tow line is usually plaited, and to avoid a knot close to the rotator, the latter is secured to the former by a knot inside an egg-shaped shell (fig. 5, Neptune pattern).,

Walker's Neptune log (fig. 6) is used for vessels of high speed. Case A contains the wheel work, and case E the spindle andsteel ball FIG. 5.-Neptune Pattern for' securing

Rotator.

FIG. 6.-Walker-'s Neptune Log.

bearings; in each case are openings, closed by sliding tubes, for examination and lubrication. In fig. 6 the cases A and E are shown open. Fig. 7 shows the dial plate. In fig. 8 the ball bearings are shown unscrewed from the body of the log, with eye, cap and spindle. They consist of two rows of balls rolling in two pairs of V races or grooves. The outer pair receive the strain of the rotator, and the inner are for adjustment and to prevent lateral movement. The balls and races are enclosed in a skeleton cage (fig. 9) unscrewing from the cap F (fig. 6) for cleaning or renewal; the adjustment of the bearings is made by screwing u the cage cap b, locked by a special washer and the two screws a, a (figs. 8, 9). If the outer races become worn, the complete cage and bearings are reversed; the strain of the line is then transferred to what had previously been the inner with practically unworn balls and races. It is for this purpose that the skeleton cage is screwed internally at both ends, fitting a screwed ring inside the cap F (fig. 6). To enable the indications of the log xvl. 28

and Bliss (Messrs Norie and Wilson). The former bears a general resemblance to the Cherub' log, but the dial plate is horizontal and the faces turn upwards. The main shaft bearings are in two sets and composed of steel balls running in steel cones and cups; the governor is an iron rodiabout 16 in. long, extremities. The Bliss resembles the Rocket with I in. balls at the

log in shape, and is secured to the taffrail 5, . b a rope or slung. Agovernor is not em- , plbyed. The blades of the rotator are ad- ° , ~ -° justable, being fitted into its tube or body 4 E, ', Q ff b by slits and holes and then soldered. The '~ " * ' Il, : 5 outer' ends of the blades are slit (fig. 12) to .- VL. . form two tongues, and with the wrench (fig. A 12) the angle of the pitch can be altered. F All patent logs have errors, the amounts ", r ~ of which should be ascertained by 1* li lQ ~7*3Q shore observations when passing a ' ttf. well surveyed coast in tideless

waters on a calm day. Constant 1 f

use, increased friction (more

especially at high speeds), and ' M W

damage to the rotator >will alter "

ascertained log error; head p fl

or following seas, strong winds,

currents and ' tidal streams also

affect the correctness;

A Log Book is a marine or sea

journal, containing, in the British navy, the speed, course, leeway, direction and force of Ithe wind, state of d barometric and therxnometric observa FIG. 8.-Ball Bearings

of Neptune Log.

the weather, an 'tions.

Under the heading “ Remarks ” are noted (for vessels with sail power) making, shorten¢Y 1

I ing and trimmin sails' and (for all t rf A* ' ~ - ~ g y

ships) employment of crew, times of

F i@!1 ' passing prominent landmarks, altering -, i g - T, , ofcourse, and any subject of interest and Llvlli iii; lzvgllvhl

Y " ' '-.,

" H:v m- "' '“ v§ '| ~,

ea " L;" 2~l

A 't“"'“"” A FIG. 9.'°'~Ball Bear-f ~-'-'i'»~“*l" 'ings of Neptune Log,

in Skeleton Case. FIG. Io.-Rocket Log. . importance. The deck log book, kept by the officers of the Watch, is copied into the ship's log book by the navigating

rr