I believe, in a speech or fireside chat, FDR once spoke of a four inch
 tail wagging a 96 inch dog.  If this is so, please supply the context.

Hi queryo,

The context in which Franklin D. Roosevelt referred to a "96-inch dog
being wagged by a 4-inch tail" is shown below:

"IV. Roosevelt's Administration - Domestic Issues - New Deal 
A. Phase I - 1933-34" 
(...)
Additional Reform Efforts 1935
(...)
"d. Public Utility Holding Company (Wheeler-Rayburn) Act 28 August
(1) Following the collapse of the financial empire of Samuel Insull ,
a number of utility companies were threatened with bankruptcy.
(2) Congress limited the possibility of controlling companies with a
small amount of capital and prevented the type of pyramiding which
Insull had done, creating several layers into a super corporation that
was only a holding company.
(3) Electric and gas holding companies were restricted to a single and
concentrated system in a single location.
(4) Roosevelt likened this pyramid to a "96-inch dog being wagged by a
4-inch tail"

Pea Ridge School District: Roosevelt's Administration
http://hawk2.k12.ar.us/HS/social%20studies/Retta%20Zumwalt/AP%20US%20HIST%20NOTES/Depression-New%20Deal.htm


Search criteria:

four inch tail wagging a 96 inch dog FDR quote
FDR OR Roosevelt quote tail wagging dog 
FDR OR Roosevelt quotation tail wagging dog 
"96 inch dog"
"96-inch dog * wagged by a 4-inch tail"


I hope the information provided is helpful. If you have any questions
regarding my answer please don't hesitate to ask before rating it.

Best wishes,
rainbow-ga

The answer given was excellent, but I would like to have known a bit more
about what FDR actually SAID (the context in this sense also) and whether it
was in a fireside chat or what.

Hi queryo,
Thank you so much for the rating and tip.
Actually that is the *only* reference I found in regard to that quote.
Had it been mentioned anywhere else, I would have let you known.
Best wishes,
rainbow~