166 
FLIGHT.—FIGURE OF 8 WAVE THEORY OF 
WING MOVEMENTS 
N the Proceedings of the Royal Institution of Great 
Britain for March 1867, Dr. J. Bell Pettigrew, F.R.S., the 
distinguished curator of the museum of the Royal College 
of Surgeons of Edinburgh, announced the startling dis- 
covery that all wings whatever—those of the insect, bat, 
or bird—were twisted upon themselves structurally, and 
that they twisted and untwisted during their action—that 
in short they formed modzle helices or screws, In June of 
the same year (1867), Dr. Pettigrew, following up his 
admirable researches, read an elaborate memoir “ On 
the Mechanism of Flight” before the Linnean Society of 
London, wherein he conclusively proves, by a large 
number of dissections and experiments, in which he 
greatly excels, that not only is the wing a screw structu- 
rally and physiologically, but further that it is a recipro- 
cating screw. He shows, in fact, that the wing, during its 
oscillations, describes a figure of 8 track similar in some 
respects to those described by an oar in sculling. This 
holds true of the vibrating wing of the insect, bat, and bird, 
when the bodies of these animals are artificially fixed. 
When, however, the creatures are liberated, and flying 
at a high horizontal speed, the figure of 8, as he points 
out, is curiously enough converted into a wave track, from 
the wing being carried forward by the body, and from 
its consequently never being permitted to complete more 
than a single curve of the 8. This is an entirely new view 
of the structure and functions of the wing, and one fraught 
with the deepest possible interest to the aeronautical 
world. It promises to solve everything. Dr. Pettigrew’s 
remarkable discovery has received an unlooked-for confir- 
mation within the last few months at the hands of 
Professor Marey, of the College of France, Paris. ‘This 
gentleman, whose skill in applying the graphic method to 
physiological inquiry is unequalled, has succeeded in 
causing the wing of the insect and bird to register their 
own movements, and has established, by an actual 
experimentum crucis, the absolute correctness of Dr. 
Pettigrew’s views. Professor Marey’s mode of registering 
displays much ingenuity, and is briefly as follows :—‘A 
cylinder revolving at a given speed is enveloped by a 
sheet of thin paper smeared with lamp black, and to this 
the tip of the rapidly vibrating wing of the insect is 
applied in such a manner as to cause it to brush out its 
track on the blackened paper, which it readily does. A 
similar result is obtained in the bird by fixing a regis- 
tering apparatus to the wing and causing the bird to fly in 
a chamber. In this case the registering apparatus is 
connected with the cylinder by means of delicate wires, 
and the registering is effected by means of electricity. In 
both cases the figure of 8 and wave movements, originally 
described and figured by Dr. Pettigrew, are faithfully 
reproduced. The way of a wing in the air has hitherto 
been regarded as a physiological puzzle of great magni- 
tude ; and well it might be, since some insects (the common 
fly for example) vibrate their wings at the almost incon- 
ceivable speed of 300 strokes per second, that is, 18,000 
times in a minute! 
It should be added that though Professor Marey 
endorses Dr. Pettigrew’s view as toa figure of 8 move- 
ment, and has recently admitted his priority in that 
observation, he is yet by no means of the same opinion 
as Pettigrew as to the explanation of the mechanical effect 
of the movements and the influence of the bird’s weight. 
Pettigrew maintains that the wings act as inclined planes 
in such a way that the bird actually rises by its own weight. 
Dr. Marey will not admit this at all, and is at issue with 
the Scotch anatomist on some other matters of moment, 
as he recently informed the writer. The beautiful and 
ingenious experiments which Dr. Marey is now carrying 
on will place these matters beyond conjecture by the light 
of experiment. 
NATURE 
| Fune 30, 1870 
A FALL OF YELLOW RAIN 
OF the 14th of February a remarkable yellow rain 
fell at Génes. The following details respecting it 
are given in a letter addressed to M, Ad. Quetelet by 
M. G, Boccardo, director of the Technical Institute of 
Génes, who examined it in concert with Dr. Castellani, 
professor of chemistry. The quantitative analysis gave 
the following results :— 
Water ives Bis 6°490 per cent. 
Nitrogenous org. ic sibstances 6°611 33 
Sandandiclay . . ; + + 657618 oF 
Oxide of iron . . 14°692 3 
Carbonate of lime 8589-3; 
Observed narrowly under the microscope, the presence 
was revealed of a number of spherical or irregular ovoid 
substances of a cobalt blue colour; corpuscles similar 
to the spores of Peziza or Permospora; spores of 
Demaziacee or Spheriacee; a fragment of a Toru- 
lacea (?); corpuscles of a pearly colour, concentri- 
ically zoned, probably small grains of fecula; goni- 
dia of lichens; very scarce fragments of Diatomacee ; 
spores of an olive brown colour; a few fragments of 
filaments of Oscél/laria, Ulothrix, and Melosira varians ; 
a fragment of Syvedra; a peltate hair from an olive leaf. 
If, instead of collecting the earth on the morning of the 
11th, when it had already been subjected to the action of 
rain falling for several hours, I had been able (writes 
M. Boccardo) to observe the phenomenon during the 
night, at the moment when it was produced, it is very 
probable that the microscope would have shown the 
existence of several kinds of Infusoria, as has been the 
case in several similar instances. 
The author notes that the direction of the wind at 
Génes during the night of the 13th and 14th was from 
the south-east, and without being exactly a hurricane as 
on the preceding few days, was still very strong. The 
temperature, previously exceptionally low, had risen, and 
probably did not fall during the night below + 4° R. 
(5° C. or 41° F.) The journals state that on that date 
a tempest devastated the coasts of Sicily. M. Boccardo, 
following P. Denza, proposes the theory that the dust 
came from the coast of Africa. ‘“ We ought not to 
forget,” he writes, “ that according to Maury’s theory of 
the circulation of the atmosphere, these clouds of dust 
may wéll have travelled a long distance before touching 
the soil of Italy, coming from beyond the Atlantic, like 
those which in 1846 spread from Guiana to the Azores, 
over the south of France and the whole of Italy.” 
RELICS OF NON-HISTORIC TIMES IN 
FERSEY 
CONSERVATION v7 DESTRUCTION 
a" the 18th of May information was received from 
Jersey of the partial demolition of some tumuli, 
hitherto undescribed in that island ; and, accordingly, two 
gentlemen, interested in the conservation of all ancient 
monuments, resolved to make a tour of inspection of the 
pre-historic remains in Jersey without delay, and the 
following is the result of the inspection :—The time was 
necessarily brief, occupying only two days, the party 
arriving at Jersey at 11 A.M. on the 19th, and leaving the 
island at 6.45 A.M. on the 21st. A summary of the route 
taken may be useful to tourists and others who may wish 
to visit all the pre-historic stone monuments in Jersey, 
as far as they are known at present. Leaving St. Helier’s 
by the St. Aubin’s road, the first attraction is the Ville 
Nouaux Cromlech, not far from the first martello tower, 
This structure was examined last year by leave of M. de 
Quetteville, the proprietor, and described at the time. © 
As now exposed to view, this cromlech appears to be 
SS oo 
