52 REPORT—1883. 
§ 1. The Notation adopted in the Tidal Reports. 
In considering the notation to be adopted, much weight should be given 
to the fact that a large mass of analysis and computation already exists 
in a certain form. We have not thus got a tabula rasa to work on, but 
had better accept a good deal that has grown up by a process of accre- 
tion. It is certainly unfortunate that a dual system should have been 
adopted, in which one set of letters are derived from the Greek and 
another from the English. 
The letters y, o, , @ are appropriated respectively to the earth’s 
angular velocity of rotation, to the mean motions of the moon, sun, and 
lunar perigee. They form the mitial letters of the words yi, ceXijvn, ipAwe, 
and perigee. There is also w, derived from the obliquity of the ecliptic. 
In another category we have M, 8S, H, for the masses of the moon, 
sun, and earth. It is unfortunate that the letter S should thus be con- 
nected with the moon in o; but it has not been thought advisable to 
change the notation in this matter. In this Report the already existing 
notation is adhered to, as far as might be without inconvenience; but it 
must be admitted that the notation is by no means satisfactory. 
‘ It isa matter of great practical utility to have a symbol for indi- 
cating special tides. In the endeavour to meet this want initial letters 
were assigned in the former Reports to each kind of tide; but, except in 
the case of M and §, for the principal ‘moon’ and ‘sun’ tides, the initials 
had no connection with the tide. Although a new system of initials 
might be devised which would have a direct connection with the tides 
to which they refer, yet it has appeared best to adhere to the old initials 
and to introduce certain new initials for the tides of long period and for 
some tides now considered for the first time. 
In the old notation the L tide was simply the tide of speed 2y —s—a. 
The values of this tide have probably been perturbed by another tide of 
speed 2y—o+ a, and this tide is supposed also to be included in L. 
Where it is necessary to refer to any other tides than those contained 
in this schedule, it will be best to use the scientific nomenclature simply 
by speed. For example, there may be a compound tide 3y—-27; and 
though this tide might be called SK, since 3y—2n=2(y—y)+y, yet 
reference to such a tide will be so infrequent as not to make the short 
notation desirable. 
Both the old and the new initials are given in the following schedule. 
[A.] Schedule of Notation. 
Initials Speed Name of Tide 
y—o—@, and 
M, ets 
M, 2(y-<c) Principal lunar series 
M, 3 (y—«) 
&e. &e. 
K, 2y Luni-solar semi-diurnal 
N Qy—304+0 Larger lunar elliptic 
ae 5 : 
sy—o—-@ an rs ryee a 
L Bet ae Smaller lunar elliptic 
; 2 Se OI 
