(546 ) 
[October, 
CORRES PON DEIN CE 
AERIAL LOCOMOTION. 
S1r,—I received, some time ago, an 
article from your valuable paper 
entitled, ‘‘ Aérial Locomotion ; Petti- 
grew versus Marey.” 
I cannot leave unanswered the 20 
pages devoted to me; but as I have 
little taste for polemics, I will not 
intrude to the same extent on your 
space. I intend to sum up the chief 
heads of that accusation, in order to 
answer them respectively. 
ist. The writer states that in a 
work on the flight of inse@s, I 
had pointed out the figure-of-eight 
track made by their wings, and that, 
on a demand of Mr. Pettigrew, I have 
acknowledged that this physiologist 
had the priority over me relatively to 
that observation. 
2nd. That, later on, ‘‘ having evi- 
dently changed my views,” I have 
declared that, in spite of this confor- 
mity, my theory and Mr. Pettigrew’s 
differ materially. 
3rd. That, in order to arrive at 
this demonstration, I had reproduced 
and altered Mr. Pettigrew’s figures. 
4th. That, concerning the flight of 
birds, I had copied Mr. Pettigrew 
in the same indiscreet manner, to 
substantiate which the writer of the 
article accumulates 14 pages of quo- 
tations, which, he says, might be 
more numerous. 
I see in this article nothing but the 
sincere expression of a great love for 
scientific truth. This feeling finds 
way in the final sentence in which 
the author assures that my process 
‘* saps the foundation of science.” 
Before bringing such an accusation 
it would have been perhaps fair for 
the critic to be enlightened on the 
question. If he had consulted Mr. 
Pettigrew he would certainly have 
learned that I never accepted his 
theory on the flight of insegts, no 
more than he accepts mine on 
the flight of birds. Under these cir- 
cumstances it was not easy to 
plagiarise. 
My severe accuser may have been 
misled by the excess of conciseness 
under which Mr. Pettigrew labours 
every time he happens to quote my 
answer to his complaints. In fa& he 
presents it in the following way :— 
‘‘T have ascertained that in reality 
Mr. Pettigrew has been before me, 
and represented in his memoirs the 
figure-of-8 track made by the wing of 
the insect, and that the optic method 
to which I had recourse is almost 
identical with his. - I hasten 
to satisfy this legitimate demand, 
and I leave entirely to Mr. Pettigrew 
the priority over me relatively to the 
question as restricted.” — Comptus 
Rendus, May 16th, 1870, p. 1093. 
Now, the suspensive stops which 
break the quotation stand for the end 
of the sentence, which runs thus: 
“‘ But we differ entirely on the inter- 
position of the trajectory seen by us 
both.” 
I do not suppose that Mr. Pettigrew 
has purposely suppressed those last: 
words: perhaps they have escaped 
him, for I am loth to believe that 
any author would intentionally muti- 
late a text; the more so as my sen- 
tence quoted in that way has no 
meaning. What would be the mean- 
ing of “ leaving the priority as 
restricted” if no restri@ion is men- 
tioned ? 
Then I had not to change my views 
in order to rejeé& Mr. Pettigrew’s 
theory on the flight of inse@s. _I re- 
jectcd it as soon as I knew it, and pre- 
cisely on account of the figure I am 
accused of having purposely altered. 
By referring to page 233 of the 
Transactions of the Linnean Society, 
vol. xxvi., and to my work entitled 
‘“‘ Animal Mechanism,” fig. 86 (page 
201 of the English translation), the 
reader will see that I have very accu- 
rately counterdrawn the figure given 
by Mr. Pettigrew, with arrows show- 
ing the direction of the motion. He 
will see, besides, that the English 
author expressly states that the wing 
of the inseé& is turned completely, 
and that its ‘ posterior or thin’ 
margin takes the place of the ““anterioz 
