He rose abruptly, as did Ray Ipsow, who, shrugging sympathetically to the boys and murmuring to Randolph, "I'll keep an eye on him," followed the eminent Yale savant, who, once outside, lost no time hailing a carriage, holding out a greenback and requesting top speed, and just like that they were off, arriving at the Palmer House, where the functionary at the desk tipped a salute from a nonexistent hat brim.
* * * * * * * * * *
"I'll keep an eye on him,"
Even Ray Ipsow has noticed the Professor is acting strangely. I guess, being the captain of his own airship, he must have taken the same course about hiding hurt feelings.
"a greenback"
The Professor's one dollar tip would be about a thirty dollar tip today. I'm assuming it's a tip because who would pay the equivalent of thirty dollars just to grab a carriage for a few blocks? Maybe that's the tourist price for when drivers spy a nutty-haired manic in a lab coat with a New England accent.
"the Palmer House"
The Palmer House was the first hotel to feature elevators, electric light bulbs, and telephones for the guests located right in their rooms! So it's just as important to Pynchon's themes as everything else he casually mentions. The Palmer House is an example of the changing times due to the rapid improvements in technology. Today, the Palmer House (now part of the Hilton chain of hotels) is supposedly the longest running hotel in America.
Famous writers who have stayed at the Palmer House (aside from Professor Heino Vanderjuice): Oscar Wilder, Mark Twain, and Frank Baum. Other famous people have also stayed there but I don't care as much about them.
The Palmer House in which the Professor is staying is the second one. The first Palmer House burned down two weeks after it was built in the Great Chicago Fire.