Mural

<spoiler> Hint: "People and dates with lasting effect."

The initials on the mural correspond to the names of the inventors, most of whose whose inventions depicted:

• EW = Eli Whitney invented the cotton gin 1794
• HD = Humphrey Davy - Demonstrated electric lamp to the Royal Society - 1806
• JW = John Whitehurst - Pulsation Engine (hydraulic pump) - 1722 other possible answer James Watt - Improved steam engine - 1763
• BF = Benjamin Franklin - Pointed light rod conductor - 1752
• GLL = George Louis Lesage - Used a single wire system to telegraph a message - 1774
• LP = Louis pasteur - Process of sterilizing milk - 1862
• GS - George Stephenson - Locomotive - 1814
• GM = Guglielmo Marconi - Radio - 1901

*AGB = Alexander Graham Bell - Phonophone (or more commonly, the telephone) - 1880

• CM = Cyrus McCormick - Inventor the Reaper - 1809
• TE = Thomas Edison - Invented phonograph - 1877

The San Francisco picture shows 3 items above the same starburst(?) pattern: A locomotive (invented by George Stevenson/GS), a telephone (invented by Alexander Graham Bell/AGB); both represented in the mural. The only one not represented is the statue of Poseidon, whose son is TRITON. ((Great! What does that have to do with the puzzle?))

The accepted answer is: triton

</spoiler>

Next book: Tomb