—— So 
August 27, 1885 | 
for the presence of fresh littoral shells in roo fathoms, we require 
the assistance of waves of sufficiently long period to affect the 
bottom at that depth, and to this extent theory in the case of 
ordinary ocean waves will not go. 
In a paper submitted last year to the Dublin Society (Prec, 
vol. iv. p. 241) I recorded observations of waves with an average 
period of 34 minutes, and suggested that these waves arose from 
wind pressure on the surface of the sea ; it would be interesting 
to know at what depth such very long, though irregular, waves 
would be capable of disturbing light deposits on the sea-bottom. 
In sheltered localities I have seen these waves attain the height 
of about three feet ; in exposed localities they would doubtless be 
higher. ARTHUR R. Hunt 
August 15 
On the Terminology of the Mathematical Theory of 
Electricity 
In a letter (NATURE, vol. xxxii. p. 76) Mr. W. J. Ibbetson 
invites suggestions for a convenient abbreviation for ‘‘total or 
resultant pressure”; at the same time he suggests the adoption 
of ‘‘ traction” for ‘‘intensity of tensile stress.” As it seems a 
pity to employ two totally distinct words to express such closely 
related ideas as intensity of tensile stress and total tensile stress, 
I would suggest that, on the analogy of pressure, ‘‘/ensure” 
should be introduced for ‘‘ intensity of tensile stress ;” and then, 
on the analogy of ‘‘tension” for ‘‘ total tensure,” ‘‘ pression ” 
for ‘* total pressure.” New words are hard to grow in a language, 
but in this case pressure and tension might interchange their 
suffixes as grafts and yield two fresh useful words. 
As regards physical and mathematical terminology in general, 
is not the time ripe for the introduction of a prefix which will 
modify the meaning of a term as the adjective ‘‘negative ” does? 
Mega and micro have proved useful for multiplying and dividing 
by a million, but how much greater scope would there be for a 
prefix ‘‘ne” or ‘“‘neg” for reversing the sign of a quantity. 
Thus negative electricity might be called ‘‘ we/ectricity,” a quan- 
tity of negative electricity as so many ‘‘ zecoulombs,” a negative 
magnetic pole as a ‘‘nepole,” a negative potential as of so many 
*“nevolts,” a negative angle could be spoken as of so many 
‘*negradions ” or ‘‘nedegrees,” a negative temperature as of so 
many ‘‘nedegrees.” In many cases there would be no appreci- 
able advantage, but if there was a general understanding as to 
the operation of the prefix ‘‘ne” in any case, it could be used 
wherever it would render the phraseology less cumbersome. 
Melbourne, July 10 WILLIAM SUTHERLAND 
An Encysting ‘‘Myzostoma” in Milford Haven 
I HAVE recently had occasion to examine a number of Covea- 
tule from Milford Haven which were kindly given to me by Mr. 
W. Percy Sladen, F.L.S., and appear to belong to the type that 
was figured by Miller under the name of Comatula fimbriata ; 
and I was surprised to find many of the pinnules presenting dis- 
tinct traces of an encysting JZyzostoma. In each of the dozen in- 
dividuals the joints of one oc more pinnules are abnormally 
developed, and in some cases they form definite cysts, which are, 
however, much smaller than those found on the pinnules of 
many Comatule and Pentacrinide from the Pacific and Oceania ; 
but they are obviously of the same character and due to the 
preserce of a parasitic JZyzostoma. According to Prof. L. von 
Graff eight species of encysting JZyzostoma are at present known, 
but they are limited to depths of 120 to 600 fathoms in the Pacific, 
the Eastern Archipelago, and the Caribbean Sea, with the 
exception of one which was dredged by the Masskr in 35 
fathoms off Cape Frio, Brazil. 
Mr. Sladen’s dredgings at Milford, therefore, have consider- 
ably extended both the bathymetrical and the geographical 
distribution of these encysting species. The five Comatule 
found in the British area have yielded six of the free-living 
Myzostomas, four of which were discovered by the Porcupine 
and Triton ; and we may probably take it for granted that the 
encysting form from Milford is another addition to the British 
fauna. 
I propose to send all my material to my friend, Prof. von 
Graff, for examination ; and as there will, no doubt, be much 
shore-dredging carried on during the next few weeks, I would 
call the attertion of British naturalists to the facts mentioned 
above, and ask them to look carefully on the pinnules of any 
Comatule which they may find for cysts or other enlargements 
of the joints. P. HERBERT CARPENTER 
Eton College, August 22 
NATURE Bi 
0 
Solid Electrolytes 
IN reference to Prof. S. P. Thompson’s letter dated August 17 
(NaTuRE, vol. xxxii. p. 366), may I be allowed to say that I 
too have observed the secondary currents which are produced 
by cells containing sulphides of silver and copper after being 
disconnected from a battery? I mentioned the fact at the 
meeting of the Physical Society on June 27, in a communication 
which will probably be printed in the Pz/. A/ag. next month. 
Indeed, the observation of these secondary currents preceded 
and led to the construction of the primary cells with solid elec- 
trolytes which I have recently described. 
I should be glad to know whether Prof. Thompson can ex- 
plain the curious effect produced by passing a battery-current 
for a moment through a cell containing a mixture of sulphide of 
copper and sulphur between silver electrodes, When the cell 
is first connected with the galvyanometer the usual secondary 
current appears, but in a few minutes, or even seconds, this 
current falls to zero and is succeeded by a third, which is in the 
same direction as the battery-current, and generally continues 
for some hours. SHELFORD BIDWELL 
August 23 
THE SQUARE BAMBOO 
= cylindrical form of the stems of grasses is so 
universal a feature in the family that the report of 
the existence in China and Japan of a bamboo with 
manifestly four-angled stems, has generally been considered 
a myth, or, at any rate, as founded on some diseased or 
abnormal condition of a species having stems, when 
properly developed, circular in section. 
Of the existence of such a bamboo there cannot, how- 
ever, now be any kind of doubt. It is figured in a 
Japanese book, the “S6 moku kin yo sii” (Trees and 
shrubs with ornamental foliage), published at Kyoto in 
1829, and the figure is reproduced by Count Castillon in 
the Revue Horticole (1876, p. 32). It is further figured in 
a work for a copy of which we are indebted to my friend 
Prof. Kinch (tormerly of Tokiyo), called the “ Ju-moku 
Shiri-yaku”—z.e. a short description of trees (of Japan). 
Finally, in 1880, Messrs. Veitch presented to the Kew 
} Museum fine specimens of the stem of the square bamboo, 
The woodcut also appeared in the Gardeners’ Chronicle for January 29, 
1876, p. 147. I am indebted to the Editor for its use on the present occasion 
