6i8 
[October, 
Analyses of Books. 
clarionet, but solely on our hearing the tones which they produce, 
whereas the artistic enjoyment resulting from viewing a marble 
statue does not depend on the white light which it reflects into 
the eye, but upon the mental image of a beautiful human form 
which it calls up.” # . . 
The author further points out the distinction between physical 
acoustics, which is essentially nothing but a section of the theory 
of the motions of elastic bodies, and physiological acoustics. 
He shows that inquiries into the processes of any of our sense- 
organs have generally three distinct parts. First, we have to 
discover how the external agent reaches the nerves to be excited. 
This may be called the physical part of the investigation. 
Secondly, we have to investigate the various modes in which the 
nerves themselves are excited, giving rise to their various sensa- 
tions. And thirdly, the laws according to which these sensations 
result in mental images of determinate external objects, — that is, 
in perceptions. Thus we have a physiological investigation for 
sensations, and a psychological investigation for perceptions. 
The results obtained for the physiological and psychological sec- 
tions of the theory of hearing are but few, imperfet and 
accidental • 
The first part of the work before us is essentially physical and 
physiological, containing a general investigation of the pheno- 
menon of harmonic upper partial tones. The second part treats 
of the disturbances produced by the simultaneous production ot 
two tones. The third part discusses the construction of musical 
scales and notes, and consequently falls within the sphere of 
aesthetics. 
A Handbook of Practical Telegraphy. By R. S. Culley. 
London : Longmans, Green, and Co. 
This work, having already reached its eighth edition, can 
scarcely be regarded as amenable to criticism. All persons who 
feel an interest in electric telegraphy— which alone falls within 
the author’s plan— will have already formed an opinion upon it, 
mainly favourable. _ . . 
The author considers in succession the sources of electricity, 
the laws of the current, the Earth as part of a circuit, magnetism 
and electro-magnetism, static and dynamic induction, atmospheric 
electricity and earth-currents, the construction of telegiaphs, 
testing, signalling, and submarine telegraphy. 
We note the remark that “ public opinion ’’ will not tolerate 
the erection of telegraph-poles in the streets of towns. We 
