The latest determinations give the length of a Martian solar day as 24h 39m 35s.
"Lectures in Navigation"
Ernest Gallaudet Draper
And as he insists in another passage: The determinations which take place in nature occur not at random, but according to a plan-an objective idea.
"The Old Riddle and the Newest Answer"
John Gerard
The vagueness of outline of the terminator makes it difficult to measure from it with precision, and somewhat more accurate determinations of the heights of lunar mountains can be obtained by measuring the length of the shadows which they cast, and the depths of craters may also be measured by means of the shadows which fall into them.
"A Text-Book of Astronomy"
George C. Comstock