Here, have this treadmill of time.

I've looked through reviews of many mid-1940s shows, and "Hour Glass", while historically important, was not well received at the time. By comparison Billboard gave much more positive reviews to "Will You Remember?" (1944-1945) and "Dr. Death" (1945).
In the opinion of the magazine though, some shows improved themselves over time. For example, Billboard panned the first episode of WABD's "Here's How" (1946) but gave the third episode a much more positive review. I don't know if that happened with "Hour Glass" though.
Do any episodes survive of 1950s Australian version of "What's My Line"?

Thank you very much for your links!
Let's be realists, let's demand the impossible.

There's also a review of the premiere of
Hour Glass
in
The Billboard
here, on page 20:
http://books.google.com.au/books?id=7xkEAAAAMBAJ&pg=PT57&dq=bi llboard+%22hour+glass%22+nbc&hl=en&sa=X&ei=tlztUo-ZH9e-sQS l2YCQAw&ved=0CDYQ6AEwAzgK#v=onepage&q=billboard%20%22hour%20gl ass%22%20nbc&f=false
For some reason, NBC made audio recordings of a lot of their early TV broadcasts. They reside at the Library of Congress. You can search to see what they have at their SONIC website:
http://www.loc.gov/rr/record/Soniccont.html

Thank you very much for this very rare and precious information! Especially the 1946 "Time Magazine" takes you back to the atmosphere of the time
Let's be realists, let's demand the impossible.

Additional info: Reviewing an episode, Life magazine called it "funny but fuzzy", "well acted but poorly produced". Even so, I think many people today would want to see it, just to see the 1940s-era acts. Some later variety series of the 1940s do have surviving episodes, such as "The Morey Amsterdam Show", "The Swift Show", etc, but these are generally not available for viewing.
Here is a link to the article, which features two pages of still photographs of the series (starting at page 84):
No, this was not the first time a "Black" performer appeared on TV. The earliest such appearance I know of, now lost, is a 1938 BBC production of "The Emperor Jones":
http://www.imdb.com/board/10259292/
However there may have been earlier appearances. Who knows?
Does Magna Carta mean nothing to you? Did she die in vain?

Great shame
Let's be realists, let's demand the impossible.

You mean the 1946 TV series? Lost, except for a few stills and the audio portion of a few episodes.
Kinescoping wasn't available until October 1947, by which point (I think) the series had ended.
So, unless the TV signals are still traveling though space, there's no chance of ever seeing it again.
Does Magna Carta mean nothing to you? Did she die in vain?