Sentence:  In contrast , Ditmars recorded the average length of seventy-two young of a 19 - foot female as 38 inches , and four young were born in London at a length of 35 or 36 inches and a <WSD>weight</WSD> of from 14 to 16 ounces . 
Meaning of the word marked with <WSD> tags:  the vertical force exerted by a mass as a result of gravity