22 Mr. W.S. Jevons on the Cirrous form of Cloud. 
the octave above, modify the state of the jet ? This is not probable; 
for if so, Savart, instead of saying “ and there are notes which have 
no influence whatever, &c.,” would have said, and all other notes 
except the preceding ones are without influence, &e. Ought these 
passages to be interpreted as admitting that the notes there sig- 
nalized are, after the unison, the most active ; and that of the re- 
maining notes of the scale, some are simply less efficacious, whilst 
the rest exert no action whatever? But in this case can we be- 
lieve that Savart would have expressed himself thus? We ma 
further remark, that the augmented fourth indicated in the first 
passage is omitted in the second. 
These vague expressions show that Savart studied but little 
the influence of notes differing from unison ; at least, under the 
present circumstances, it appears to us that neither a partial dis- 
agreement nor an absolute agreement between our theoretical 
conclusions and experimental facts can be deduced. Happily, 
Savart afterwards sought to augment the energy of the action of 
the vibrations of the instrument; and the effects, as he then 
describes them, ought, as we shall soon see, to be regarded as 
altogether confirmatory of our conclusions. 
[To be continued. ] 
Il. On the Cirrous form of Cloud. 
By W.S. Juvons, Assayer, Sydney Branch of the Royal Mint*. 
IRRUS isa name denoting those light fibrous tufts, branches, 
or scrolls of cloud often seen at great elevations in the 
atmosphere ; and the general adjective-term cirrous may be con- 
veniently applied to any appearance in clouds of this fibrous or 
feathery character. 
The term was originally proposed by the meteorologist Howard; 
and in defining the cirrus as “ Parallel, flexuous, or diverging 
fibres, extensible by increase in any or in all directions,” he left 
little to be desired either as to accuracy or conciseness of de- 
scription. 
Though so happy in his descriptions and remarks on the ap- 
pearance of the cirrus, he merely attempts to explain its form- 
ation by comparing it with the well-known experiment of the 
electrified lock of hair. In this latter phenomenon, the hairs or 
other fibres employed, being all charged with the same kind 
of electricity, become mutually repellent and spread out to the 
greatest possible distances from each other. The cloud-fibres, 
on the contrary, are generally seen to run parallel to each other, 
often, indeed, to great distances and throughout the most various 
* Communicated by Thomas Grahain, Esq., F.R.S, 
