Thus if the plane is normal to Or, the resultant thrust R =f fpdxdy, (r) and the co-ordinates x, y of the C.P. are given by xR = f f xpdxdy, **yR** = f f ypdxdy.

The components of velocity of the moving origin are denoted by U, V, W, and the components of angular velocity of the frame of reference by P, Q, R; and then if u, v, w denote the components of fluid velocity in space, and u', v', w' the components relative to the axes at a point (x, y, z) fixed to the frame of reference, we have u =U +u' - **yR** +zQ, v =V +v -zP +xR, w=W +w -xQ +yP.

Pwllheli commands a good view of Merionethshire and of the Snowdon range, with the entire sweep of Cardigan Bay, Carreg **yr** ymbill (gimlet stone) at the mouth of the harbour, Abersoch and St Tudwal's Islands.

Among his publications were the well-known quarterly magazine Y Traethodydd (" The Essayist"), Gwyddoniadur Cymreig (" Encyclopaedia Cambrensis"), and Dr Silvan Evans's English-Welsh Dictionary (1868), but his greatest achievement in this field was the newspaper Baner Cymru (" The Banner of Wales"), founded in 1857 and amalgamated with **Yr** Amserau (" The Times") two years later.

Summing up for all the forces of the given system, we obtain a force R at 0, whose components are X~(X,), Y~~(**Yr**), Z~(Z,), (6)

If P, be the force at (Xr, **Yr**, Zr), acting,in the direction (1, m, n), the formulae (6) and (~) reduce to X = Z(P).

Let **yr** be the linear velocity of the point E fixed in the plane of axes AOB.

Accidence.-Welsh has a definite article **yr**, " the," which becomes r after a vowel, and y before a consonant unless already reduced to r.

Thus **yr** oen, " the lamb," i'r ty, " into the house," yn y ty, " in the house."

The relative pronouns are nominative and accusative a, oblique cases ydd, **yr**, y.

The expressions **yr** hwn, y neb, " the one," are mistaken for relatives by the old grammarians; the true relative follows: **yr** hwn a =" the one who."

Affirmative particles: **yr**, fe.

In Welsh the name is Ynys **yr** Afallon, usually interpreted "Isle of Apples," but possibly connected with the Celtic tradition of a king over the dead named Avalloc (in Welsh Afallach).

As such he is e **yr** j rcop (" leader"), oiKivTfs (" founder"), 8cop.arirns (" god of the home").

Above the river bed, and the Craig-**yr-allt** Goch dam, subject to a head of 133 ft.

**Yr** Cr ii ?