204 
NATURE 
[ Fuly 1, 1886 
furnaces and engines, but to obtain the same result the cost of 
gas is greater than that of coal. Although the directors of the 
gas companies of the Metropolis are apparently not unwilling to 
advance the cause of smoke abatement, and thereby of public 
sanitation, by making a reduction in the price of gas used for 
trade purposes, they are prevented doing so by their Acts of 
Parliament. The Council are keeping the matter in view, and 
watching a favourable opportunity to urge the Government to 
grant the necessary powers. 
Correspondence has been carried on on the subject of the gas 
stoves at the Bank of England, insisting on the necessity of flues 
being provided to carry off the products of combu tion from all 
gas stoves used for warming purposes, and letters have been 
received thanking the Institution on behalf of the clerks for calling 
the attention of the Bank authorities to the matter. Voluminous 
correspondence has also been carried on with makers and 
inventors of stoves and smoke-prevention appliances, and of 
patent fuels, and with others, giving information and sug- 
gestions on points connected with the subject too various to be 
set out. 
During the year several tests have been carried out by the 
Institution, and they have now under consideration the prepara- 
tion of another volume of detailed reports of tests. The 
volume would include tests of various forms of furnaces, steam 
and other boilers, blow-pipe furnaces, smoke-preventing appli- 
ances, ventilating fans, non-conducting compositions, mechanical 
stokers, condensers, gas cooking and heating stoves, and various 
heating and cooking appliances using gas and coal as fuel. 
The Council had at one time intended to exhibit at the 
Varkes Museum typical forms of heating and smoke-abatement 
appliances, but for various reasons they considered it undesirable 
to carry out the scheme, and they propose instead to promote 
periodical exhibitions of special heating apparatus, or new 
methods of heating and smoke prevention, as opportunity may 
offer. 
In connection with this branch of the subject, reference may 
be made to the exhibition of the Sanitary Institute held at 
Leicester in September, at which various stoves and smoke- 
preventing appliances were exhibited. Exhibitions of gas stoves 
for heating and cooking purposes have also been held in many 
of the chief provincial towns during the year. 
A memorial, praying for a grant from the surplus funds of 
the International Health Exhibition, signed by the Duke of 
Westminster and other influential persons, was unavailing, 
although the object of this Institution so directly affects public 
health, the improvement of which was the avowed aim of the 
Health Exhibition. This is much to be regretted, as the lack 
of funds not only militated against the general operations of the 
Institution, but it prevented the Council establishing a testing 
department, which is a necessary adjunct to the Institution for 
the advancement of its objects. 
During the year a lecture given in the Parkes Museum by 
Mr. T. Fletcher, of Warrington, on Smoke Abatement, and a 
pamphlet containing three prize essays on the same subject, 
have been printed by the Institution and circulated. A paper 
by Mr. W. R. E. Coles, on the Hygienic, Moral, and Economic 
Aspects of the Smoke Question, read at the Leicester Congress 
of the Sanitary Institute, is now being prepared for circulation. 
By order, E. WHITE WALLIS, 
Secretary 
THE WINGS OF BIRDS? 
“THE power of flying through the air is one of the principal 
characteristics of the class of birds. Although some 
members of the other great divisions of the Vertebrates—the bats 
among Mammals, the extinct pterodactyle among Reptiles, the 
flying-fishes among Pisces—possess this power ina greater or 
less degree, these are all exceptional forms, whereas in birds the 
faculty of flight is the rule, its absence the exception. Among 
Invertebrates this power is possessed in a very complete degree 
by the greater number of insects. 
In the normal structure of the vertebrate animals there are 
two pairs of limbs, anterior and posterior, never more. It 
often happens, however, that one pair, and sometimes both, are 
suppressed, being rudimentary, functionless, or entirely absent. 
Flight is always performed by the anterior or pectoral pair, 
more or less modified for the purpose. The super-addition of 
* Abstract of Lecture by Prof. W. H. Flower, LL.D., F.R.S., at the Royal 
Institution. February 19, 1826. 
wings to arms, as in the pictorial representations of angels, has 
no counterpart in nature. The wings of the bird, the bat, the 
pterodactyle, and flying-fish, are the homologues of the arms of 
man, the fore-legs of beasts. In the flying-fish the power is 
gained simply by an enlargement of the pectoral fin, and the 
function is very imperfect; in the pterodactyle, by immense 
elongation of one (the outer) finger, and extension of the skin 
between it and the side of the body ; in the bats, by elongation 
of the four outer fingers, and extension of a web of skin between 
them and the body. In the bird the flying organ is constructed 
mainly of fepidermic structures, peculiar outgrowths from the 
surface, called /eathers—modifications of the same tissue which 
constitutes the hair, horns, scales, or nails of other animals. 
Feathers are met with only in birds, and are found in all the 
existing members of the c’ass, constituting the general covering 
of the surface of the lody. 
The framework to which the broad expanse formed by the 
feathers is attached is composed of hones, essentially resembling 
those of the fore-limb of other Vertebrates. ‘he distal segment, 
manus, or hand, in the vast majority of birds, has three meta- 
carpal bones and digits, the former being more or less united 
together in the adult state. The digits appear to correspond 
with the pollex, index, and medius of the typical pentadactyle 
manus ; the second is always the longest. Both it and the 
pollex frequently bear small horny claws at their extremity, con- 
cealed among the feathers and functionless, but very significant 
in relation to the probable original condition of the avian wing. 
These claws are altogether distinct from the large, and often 
functional, spurs developed in many species from the edge of 
the metacarpal bones, resembling bo h in use and situation the 
corresponding weapons in the hind-feet The third digit dues 
not bear a second phalanx or claw in any existing bird. 
The quills, remiges, or flight-feathers attached to the bones of 
the manus (called ‘‘ primaries”), never exceed twelve in number, 
and are (as has been recently shown hy Mr Wray) in the very 
great majority of birds distributed as follows :—Six, or in some 
few caves (flamingo, storks, grebes, &c.), seven to the meta- 
carpus ; of the remainder or digital feathers, one (ad-digital) is 
attached close to the metacarpo-phalangeal articulation, and rests 
on the phalanx of the third digit ; two (d-d/gita/) have their 
bases attached to the broad dorsal surface of the basal phalanx 
of the second digit, which is grooved to receive them ; the re- 
mainder (fre-digita/) are attached to the second phalanx of the 
same digit. These last vary greatly in development, in fact their 
variations constitute the most important structural differences of 
the wing. In most birds there are two ; the proximal one well 
developed, the distal always rudimentary; but the former may 
show every degree of shortening, until it becomes quite rudi- 
mentary, or even altogether absent, as in /7zgi//id@ and other 
‘‘nine-primaried” birds, in which there are six metacarpal 
remiges, one ad-digital, two mid-digital, and no pra-digitals, or 
only a very rudimentary one. The smaller feathers at the base 
of the quills, called upper and under coverts, have an equally 
regular arrangement. The webs or vanes of all the flight- 
feathers are made up of a series of parallel ‘‘ barbs” which 
cohere together by means of minute hookleis, and so present 
a continuous, solid, resisting surface to the air. 
Such is the characteristic structure of the wing in almost all 
carinate birds, whether powerfully developed for flight, as in 
the eagles, albatrosses, or swifts, or whether reduced in size 
and power to practically useless organs, as in the extinct great 
auk, the dodo and its kindred, weka rail, notornis, cnemiornis, 
&c., most of which, being inhabitants of islands containing n+ 
destructive land mammals, appear to have lost the principal 
inducement, and with it the power, to fly. 
In the penguins (Spheniscomorphe) the feathery covering of 
the wing entirely departs from the normal type. Each feather 
is like a flattened scale frayed out at the edges, the barbs are 
non-coherent and have no hooklets. They form an imbricated 
covering of both surfaces of the wing, including the broad 
patagium which extends from the cubital side of the limb, but 
appear to have no definite relation to the bones, and cannot be 
divided into distinct groups, corresponding to those described 
above. The structure of the wing separates the penguins sharply 
from all the other carinate birds. 
The Ratite, or birds without keel to the sternum, form 
another very distinct group, distinguished by the rudimentary or 
imperfect condition of the remiges or quills, which never have 
coherent barbs, and are therefore unfitted to the purpose of 
flight. In the ostrich and rhea the bones, though comparatively 
PO 6 he ter Ne oe UO eee ey wr es 
