VOL. XXXIII.] PHILOSOPHICAL TRANSACTIONS. 1^ 



trunk of the body, will become shorter. But when this superior weight shall 

 be entirely removed, by placing the body in a horizontal posture, as it always 

 is when we are in bed, the compressed cartilages will, by their natural elastic 

 power, begin gradually to enlarge themselves, till they recover the same ex- 

 panded state they enjoyed before they were forced to give way, and yield to the 

 incumbent pressure ; thus producing a considerable alteration in a person's 

 stature, as mentioned in the preceding letter. For if we only consider, that 

 the beforementioned compressive power will lessen the thickness of all the 

 cartilages, in proportion to the quantity of matter they contain; and that there 

 are usually reckoned about 24 in number, it will be no difficult matter for us to 

 apprehend, that their natural expansion being recovered by our customary re- 

 pose, the aggregate of the whole of the expansions may amount to about an 

 inch. Now if the alteration be so considerable as this, occasioned only by the 

 bare incumbent weight of the superior parts of the body, without any additional 

 force applied to compress the cartilages yet closer, how much more may we 

 reasonably imagine it would be, were the experiment tried on those persons, 

 whose usual employment it is to carry heavy burthens. This alteration is not 

 to be expected to be the same in aged persons, as in those that are younger ; be- 

 cause the cartilages, as we advance in years, gradually grow harder and harder, 

 till many of them arrive to the solidity of a bone; that is, by degrees they lose 

 their spring or expansive power, and at length continue in a compressed state of 

 rest. And this is doubtless one principal cause, why old people not only seem 

 to have lost somewhat of their former height, but are actually shorter. 



A Catalogue of 50 Plants from Chelsea Garden, presented to the Royal Society 

 for the Year IT 23, by the Company of Apothecaries of London, pursuant to 

 the Direction of Sir Hans Sloane, Bart. N" 383, p. QS. 



Observatio7is on the Farialiun of the Horizontal Needle at London, in the latter 

 Part of the Year 1722, and the beginning of 1723. By Mr. George 

 Graham, F. R. S. N° 383; p. 96. 



The figure of the three needles, with which the experiments were made, was 

 prismatic; their lengths were nearly 12.2 inches; their ends, which pointed to 

 the divisions, being filed to an edge, which made a fine line perpendicular to 

 the horizon. The caps of two were of crystal, the other of glass; they were 

 well polished on the inside, in that part which touched the pin they moved on. 

 The box was brass, and of a breadth sufficient to admit of 20° on each side the 

 middle line, and covered with a piece of ground glass. The circular arches at 



E 2 



