How does the TT learn that the morlocks are carnivorous?

The TT learned the Morlocks were carnivorous when he smelled the blood and saw the meal laid out on the table in their abode.

Necessarily my memory is vague. Great shapes like big machines rose out of the dimness, and cast grotesque black shadows, in which dim spectral Morlocks sheltered from the glare. The place, by the by, was very stuffy and oppressive, and the faint halitus of freshly shed blood was in the air. Some way down the central vista was a little table of white metal, laid with what seemed a meal. The Morlocks at any rate were carnivorous! Even at the time, I remember wondering what large animal could have survived to furnish the red joint I saw. It was all very indistinct: the heavy smell, the big unmeaning shapes, the obscene figures lurking in the shadows, and only waiting for the darkness to come at me again!