It is possible to navigate back through the .jpegs.
But not that easy to find one from a given date.
The way that you do it is this.
get a page from the log that you like - say
H.M.S Crocus - this is the 8th of September 1921http://oldweather.s3.amazonaws.com/ADM%2053-74526/ADM%2053-74526-120_0.jpg
take a note of the last few numbers - the ones before the .jpg
the last number is either a 0 or a 1
0 = the left hand page of the open log -
in this case the even date, the 8th of September
1 = the right hand page of the log -
so changing the last number to a 1 ADMxxxx-120_1.jpg
will give you the page for the 9th of September
so ADMxxxxxx-120_x.jpg will take you to a pair of open pages - a spread.
to navigate back - just reduce the ADMxxxx-120_x.jpg
by the number of spreads that you want to skip.
Skip ten spreads back to ADMxxxxxxxxxxx-110_0.jpg and it should land you twenty days earlier.
it gives the page for 19th of August.http://oldweather.s3.amazonaws.com/ADM%2053-74526/ADM%2053-74526-110_0.jpg
I'm sure it would be easy enough to figure out roughly how many spreads you would need to reduce by to get wherever you want.
btw. this is quite safe. if you put in a number that has no page associated you will just get an xml error page, just click the back button and you'll be returned to where you last were.
I haven't explored the numbers preceeding these, they probably refer to volumes (ie individual log books) and perhaps vessels.
If anyone figures it out be sure to post it.
and perhaps the pages of the most interesting engagements too.