We think we've found the first time that the use of a
analogy between electrical current and water flow was
presented to the public:
From "Modern Electrics", October, 1911, we read:-

BOOK REVIEW.
ANALOGIES BETWEEN BATTERY CURRENT AND WATER FLOW
        A very interesting little book, of 20 pages, and with
many illustrations, has been published by the National Carbon
Co., of Cleveland, O., and which may be obtained free by our
readers on application to that company.
        Many who work with electricity, and particularly those
who handle dry cells and are not versed in electrical terms
generally, are confused by the technical names employed in
describing current. Acting on this knowledge, of the lack of
simple explanations, describing the different electrical terms
and units, the booklet has been published.
        It compares all the electrical terms with the flow of
water. This makes explanations simple and very easily under-
stood. All readers who are not quite sure as to the meaning
of certain electrical terms, would be well repaid for sending
for the above mentioned book.
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For those persons not aware, a "Blue Book" has been published
for many years in Manitoba, listing the call letters of all
Manitoba Hams, with other associated information. The first
'Blue Book' in Manitoba was compiled by the Amateur Radio
League of Manitoba, the Winnipeg Amateur Radio Club, and the
University of Manitoba A.R.C., and was the joint effort of two
hams, Bert Anderson, VE4AP and Bill Bowman (now VE4UB).

But we were not the first to have a 'Blue Book'. In 1909,
Modern Publishing Co., 233 Fulton Street, New York, USA,
published the first of what was to be the Annual Official
WIRELESS BLUE BOOK of the Wireless Association of America.

"This Wireless Blue Book contains the following:
U.S. Land Stations (also Canadian Stations), government and
commercial; U.S. Ship Stations (including foreign ships touching
U.S. ports), government and commercial; U. S. Amateur Stations.
This book is arranged in such a manner that ALL calls are
classified ALPHABETICALLY. Therefore, no matter from what part
of the country or the sea the wireless call comes, you will
immediately locate the sender.
In addition, we furnish with each book a Wireless Map of the U.S.
Price by mail, 15c.
When remitting, send Money Order, or Bank Draft, stamps or cash,
no checks, please."
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And for all you old-timers, remember this?
Eitel-McCullough, Inc. announces another great EIMAC achievement..
EIMAC 35T.
The EIMAC 35T embodies the following features:
Plate and grid fabricated from TANTALUM
Plate terminal at top of envelope
Rugged thoriated tungsten filament
Hard glass (Nonex glass) permits maximum safe heat dissipation
making possible the small physical size of the EIMAC 35T
The EIMAC 35T will be available at leading dealers after April 15
1936. Price, $8.00

Also in 1936, RCA announced the production of their latest:
804 (transmitting pentode), 805 (high-mu transmitting triode,
and 836 (half-wave, high vacuum to sub 866 mercury-vapour tube) plus
the soon-to-be-on-the-market ACR-175 Amateur Superhet Receiver.
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End of HISTORY4 de Gil, VE4AG