Sentence:  Although the tape was run for over 1 <WSD>hr.</WSD> , a steady state was not reached , and it was concluded that the reason for this was that the back pressure of the manometer was built up from the material fed from between the blocks and this was available at a very slow rate . 
Meaning of the word marked with <WSD> tags:  a period of time equal to 1/24th of a day