Smithsonian Institution 
Washington, d. C. 
ALL CORRESPONDENCE 
.MOULD BE ADDRESSED 
TO THE SECRETARY 
S. P. LANGLEY. 
( rn . y / , 1900. 
Deariir. Holmes: 
Your Mr. D. F. Murphy’s printed c orntomi cat i on 
argues a good deal of careful and intelligent observation 
on tHe "Jolm Crow”, (more indeed titan I Mad ezpected), but 
it is combined witli an ignorance of tine fundamental prin- 
ciples of tiie subject. He is, I tHinM, in error in His 
letter / in saying tiiat it will be impossible to pitot ograpli 
tHese witli advantage:-. it is nearly impossible now, witli tide 
present apparatus, to do more titan you Have already done, 
but I am, as I tHinfc I told you, arranging for a twin pair 
of simultaneously acting cameras wHicH will give every 
element of tHe bird’s position at every observation. 
I shall be pleased to see tHis Mr. MurpHy wlien 
ne comes; and as to tHe proposed cameras, if tHe subject 
