SMITHSONIAN INSTITUTION 
S. P. LANGLEY, Secretary 
G. BROWN GOODE, Assistant Secretary, 
in charge ofU. S. National Museum 
UNITED STATES NATIONAL MUSEUM 
July 22, 1891, 
Doctor Sereno Watson, 
Curator of the Harvard Herbarium, 
Cambridge, Massachusetts, 
My dear Sir: 
In the absence of Professor Langley, I 
beg to reply to your letters of May 20th, and June 
17th, relating to the Ball Herbarium, As you said 
the matter was not urgent, we have intenti onally 
delayed answering until some available person was 
found whom we could send to assist in the work of 
overhauling the herbarium and making it up into 
sets. Your suggestion that the work be done in 
Cambridge is entirely satisfactory, and if you have 
assistants who can be detailed to do the work, we 
will be glad to pay our share of the expense. If, 
on the other hand, you have no one in mind, the 
