34 Mr. W.S. Jevons on the Cirrous form of Cloud, 
(and vice versd), which will produce cirrostratus, and explain the 
fact that this compound form of cloud is more common than 
either the simple cirrus or stratus alone. 
If it be said that the compound term denotes two kinds of 
actions going on at different parts of the same cloud, and not 
necessarily in the same portion of air, that, for instance, cumulo- 
stratus (sometimes called, I think, the anvil-shaped cloud) is a 
cumulus extending at top into a stratous projection, I answer 
that the term becomes too indefinite, since a cumulus and stratus 
may be combined together in several other ways, so that anvil- 
shaped cloud is a more exact and desirable description. 
But if even cumulostratus and nimbus should be retained on 
account of their well-established use, the term cirrocumulus is 
still outlying as entirely unmeaning and improper. Howard 
himself thus describes this modification :—“ The cirrocumulus is 
formed from a cirrus, or from a number of small separate cirri, 
by the fibres collapsing, as it were, and passing into small 
roundish masses, in which the texture of the cirrus is no longer 
discernible, although they still retain somewhat of the same 
relative arrangement.” The cirrocumulus is produced from the 
cirrus when the filtermg action is from some cause or other 
stopped ; watery particles once precipitated do not always eva- 
porate again immediately the action stops, since they may be 
surrounded by air perfectly saturated with moisture; but the 
forms of the streamlets or cirrous fibres are soon broken up, and 
the cloud-matter aggregates into small rounded bodies. There 
is nothing in the formation of this sort of cloud which in the 
least resembles a cumulous action, and it occurs indeed in a 
totally different region of the atmosphere from true cumulus ; 
the term cirrocumulus is therefore improper, as well as but im- 
perfectly descriptive of the mere appearance of the cloud. I 
should propose in its place the short term cirroidus, or cirroid 
cloud, which sufficiently expresses its undoubted cirrous origin, 
and half-cirrous appearance. 
Howard’s nomenclature by no means exhausts the variety of 
common species of cloud ; as there is cirroid cloud derived from 
a former cirrus, so there may be masses of cloud-matter remain- 
ing from former cumuli and strati, equally important and fre- 
quently occurring in the atmosphere, though mot so distinctive. 
in appearance. For those species I would propose the corre- 
sponding terms cwmuloid and stratoid cloud; or if substantives 
be necessary, cumuloidus and stratoidus. 
Every meteorologist must have felt the insufficiency of Howard’s 
terms alone ; and until an additional and numerous set of terms 
be devised to denote definite atmospheric phenomena, it will 
always be impossible, as at present, to record the state of the sky 
