1905-6.] A New Form of Harmonic Synthetiser. 233 
which the mathematical theory presented in this paper indicates 
how this deviation could, if necessary, be still further reduced. 
The instrument is eminently simple and inexpensive in con- 
struction, one of the author’s objects being to discover whether 
an apparatus so designed would give really satisfactory results. 
The present machine (which, it should he noted, has no slides 
anywhere, hut only pivots) does its work well; and it has the 
further advantage of being compact and portable. It is hoped 
shortly to issue a further paper on this subject. 
For some specimens of the traces produced see pages 211 
and 213. 
{Issued separately Jidy 12, 1906.) 
