WCP276

[1]

Parkstone, Dorset.

Oct^r. 18th. 1896

My dear Violet¹

I send you the books you want, also two "Centuries" & Will’s² Joan of Arc. There are no more O. S. articles in Fortnightly. I am & have been very busy, & no news except a new chess-player, good I believe. As you are to have your "bike" soon I send you a checque for the Amount. Mrs. Fisher³ has been here last Saturday to Monday discussing about her new book. No beetles to be found now. Cannot send snails with books.

As to the pendulum experiment — [2] the reason is, that any heavy object either rotating, as a wheel, or swinging, as a pendulum, keeps in one plane, & requires considerable force to move it ^angularly out of that plane. The plane a heavy pendulum swings in, if the ball is suspended by a very long thin wire, is a plane in space. But as the whole pendulum & room in which it swings is carried round with the earth, the plane would have to change if it kept in one apparent plane as in the pendulum of a clock. The free pendulum does not change its [3] plane, but the room & floor do revolve, therefore the fixed plane of the pendulum-swing appears to revolve around the room. If you have any of your school rooms with a hook in the ceiling you can try it. get a round or cylindrical weight, about 28 lbs. suspend it by a very thin piece of steel wire, draw it about 3 or 4 feet out of the perpendicular & fasten it by a thin string. Get the room closed so that there is no draught, & burn the string [.] Then the pendulum <brings> to [4] swing in a certain line which you can mark. In an hour it will be found to be swinging in a different plane, moving opposite to the hands of a watch. It can be seen to have moved I think in a quarter of an hour.

Will’s address. is — He says he will be here every week as long as he is at Southampton so you can write here. Mrs. Julia Dawson⁴ of "The Clarion" would like you to call on her. She is an invalid and cannot walk much. Her address is 33 Gresford Avenue, Sefton Park. I think you will like her.

The Bike makers will take the checque. If you are to have discount for cash ask them to give it you.

Your affectionate Pa | Alfred R. Wallace [signature]