,. hat: P 
7 ~ 
_ May 12, 1923] 
een such a wonderful subject.” It seems to us that 
‘there is room for a book on the subject of the ethics 
of “istening-in”’ to urgent personal and farewell 
messages from, for example, passengers on board ship. 
This method of obtaining interesting and amusing 
knowledge would not appeal to every one. 
(rt) Prof. Hausmann’s book describes in an excellent 
and simple way the methods and apparatus used for 
eiving radiophone speech and music. Nine of the 
most eminent experts in America have co-operated 
to produce a thoroughly good book which can be 
readily understood without special technical knowledge. 
_ (2) Mr. Keen’s book deals not only with the general 
principles of direction-finding, but also with the con- 
structional details of the installations required for 
shore service and for the navigation of ships and air- 
craft. It will be appreciated by the expert, for, 
although the discussion of problems is usually rather 
ementary, it is very thorough. The nomenclature 
of the subject is not yet fixed and so the author occa- 
sionally uses alternative words. We thus find the 
“cardioid,’ the “heart-shape,” and the “apple” 
diagram of reception. Occasionally the author gets 
tired of writing about the ‘“ Marconi-Bellini-Tosi ” 
system and refers to it simply as the M.B.T. system. 
The notes on field and nautical astronomy given in 
the appendix are good and will be helpful to the 
eng neer. 
— (3) Colonel Crawley’s little book on wireless is 
popular and interesting. He points out that the 
enthusiasm for broadcasting may have drawbacks. 
In the United States it is sometimes called ‘ radio- 
flu.” The purchase of a cheap set may lead to grievous 
disappointment. He gives a thoughtful discussion of 
the Imperial Wireless Chain. 
(4) Mr. Coursey discusses the essentials of a radio- 
phone and how it operates. He uses “ wireless ” and 
“radio” indiscriminately. The book is nicely got 
up and will be useful to beginners. 
(5) The fifth book on our list will meet the require- 
ments of those who desire to construct their own 
apparatus. A detailed description is given of a high- 
grade crystal receiver suitable for the reception of 
the broadcast concerts and radio time-signals sent out 
by the Eiffel Tower station in Paris. It must be 
remembered, however, that the concerts broadcasted 
by the Hague are quite inaudible in even a good 
crystal receiver connected with a large aerial. They 
can be heard only by suitable valve apparatus. 
(6) Full particulars are give in Mr. Ainsley’s little 
book for erecting various kinds of masts and aerials. 
Although it is not essential to possess an outside aerial 
with every receiving set, yet, when economy is a con- 
sideration, it is an advantage to have one. A strong 
NO. 2793, VOL. 111] 





























NATURE 
' 36-foot mast is shown the cost of the material for 
629 
which was only 25s. 
(7) In the last book on our list the author describes 
an ingenious method of learning the Morse system 
rapidly. This book should prove very helpful to 
many amateur radio-telegraphists. 
Those intending to listen-in to the broadcasting 
must remember that even the best loud - speaking 
telephones appreciably distort speech and music. 
They cannot be used, also, unless the signals be so strong 
that they are uncomfortably loud on the radiophones. 
As a general rule, if it is desired to make signals audible 
in a room by means of a “ loud speaker ” it is necessary 
to add a two-valve magnifier to a set which would give 
comfortable hearing when used with radiophones. 
The two-valve magnifier itself appreciably distorts 
speech, thus adding to the troubles of those who 
listen-in. 

The “Chemical” Sense. 
Smell, Taste, and Allied Senses in the Vertebrates. By 
Prof. G. H. Parker. (Monographs on Experimental 
Biology.) Pp. 192. (Philadelphia and London : 
J. B. Lippincott Co., 1922.) ros. 6d. net. 
HE mechanism of the senses of smell and taste 
i§ is apt to be unduly neglected, probably on 
account of the fact that in civilised man these senses 
do not play a large part in intellectual processes. But 
they bring before us some interesting problems as to 
the nature of receptor organs in general. It will be 
remembered that the object of such organs is to excite 
a set of nerve fibres on the incidence of some external 
agency of such a kind or intensity as to be unable to 
affect these nerve fibres directly. This is done by the 
production of some powerfully stimulating agent in 
the receptor mechanism at the terminations of these 
nerve fibres. 
It is difficult to define satisfactorily the difference 
between taste and smell. If it be said that the former 
relates to substances in solution, whereas the latter 
relates to vapours, we are met with the fact that even 
vapours must be dissolved in the watery layer covering 
the olfactory cells. Moreover, the presence in fishes 
of a mechanism which appears to be the same as that 
of smell in air-breathing organisms suggests the need 
of some other criterion. Prof. Parker directs attention 
to the lipoid solubility of odorous substances and to 
the existence of hairs composed of lipoid material on 
the olfactory cells. The relation of surface tension 
and adsorption has also been brought into connexion 
with odorous properties. When we come to attempt 
to correlate either smell or taste with chemical com- 
position we are met with serious difficulties. 
TI 
