Dr Ellis had pipes (now preserved in the Royal Institution, London) made to reproduce both these pitches at 31 in.
(as are all pitches in this article), is a' 393.2.
Sir Frederick Gore Ouseley's comparison of the church and chamber pitches of Orlando Gibbons (vide Ellis's lecture) clearly shows the minor third in Great Britain in the first half of the 17th century.
Scheibler, by his simple and accurate tonometer, has recorded pitches in Vienna about 1834 from a1 433.9 to 440.2.
Table III., showing orchestral pitches obtained in 1899, for the measurements of which the writer is responsible, prove how chimerical it is to hope for greater accuracy than is found between 435 and 440 vibrations a second for a', inasmuch as temperature must always be reckoned with.
Where h, k, are the pitches of the two given screws.
It is to be noticed that the parameter c of the cylindroid is unaltered if the two pitches h, k be increased by equal amounts; the only change is that all the pitches are increased by the same amount.
Hence we can adjust these so that the surface shall contain the axes of the two given screws as generators, and that the difference of the corresponding pitches shall have the proper value.
In particular cases the cylindroid may degenerate into a plane, the pitches being then all equal.
P p are the pitches of the two screws.
74~ Differential Screw.On the same axis let there be two screws of the respective pitches Ps and p1, made in one piece, and rotating with the angular velocity a.
The breaking is done by passing the stalks between grooved or fluted rollers of different pitches; these rollers, of which there may be from 5 to 7 pairs, are sometimes arranged to work alternately forwards and backwards in order to thoroughly break the woody material or " boon " of the straw, while the broken " shoves " are beaten out by suspending the fibre in a machine fitted with a series of revolving blades, which, striking violently against the flax, shake out the bruised and broken woody cores.
The whole state lies on the south-western exposure of a great roof whose crest, along the continental divide in western New Mexico, pitches southward.