4-35 



cumstances as the creeper, its tendrils manifested the same tendency 

 to recede from the light. When first emitted, they pointed upwards ; 

 but the angle gradually increased, and ultimately they pointed di- 

 rectly downwards when no object was within their reach to which 

 they could attach themselves. The ultimate direction was in all in- 

 stances towards the darkness of the ground, whether the plants were 

 trained upwards, horizontally, or downwards. 



There was, however, this difference observable between the ten- 

 drils of the vine and those of the Virginia creeper : those of the vine 

 could be made to return to any position which they had quitted, by 

 changing the direction of the light ; but those of the creeper never 

 returned to a situation from which they had once receded ; as the 

 tendrils of the vine are, moreover, separated into two divisions, they 

 do not often fail of coming into contact with adjacent objects ; and 

 the effect of contact is almost immediately visible. They bend more 

 firmly toward the body, and attach themselves by twining round it. 



The organization of the tendril, by which it is adapted to perform 

 these motions, appears to the author very similar to that of the young 

 succulent shoot. It is abundantly provided with vessels ; and it seems 

 not improbable that a very considerable quantity of the moving fluid 

 of the plant passes through them, and that there is a close connexion 

 between their vascular structure and their motion, as appears more 

 especially in the act of grasping an object. The external pressure of 

 the body on one side will probably impede the motion of the fluids on 

 that side of the tendril, and occasion greater extension of the oppo- 

 site side in giving passage to a greater proportion of sap. In con- 

 formity to this explanation, it is observed, that the sides of the ten- 

 drils that are in contact with the substance embraced are visibly com- 

 pressed and flattened. 



Observations on the Measurement of three Degrees of the Meridian 

 conducted in England by Lieut. -Col. William Mudge. By Don Jo- 

 seph Rodriguez. Communicated by Joseph de Mendoza Rios, Esq. 

 F.R.S. Read June 4, 1812. [Phil. Trans. 1812, p. 321.] 



After tracing the history of the several measurements that have 

 been made from time to time in different parts of the world, the au- 

 thor observes, that little doubt would have remained as to the earth 

 being flattened at the poles, had not the English measurement given 

 an opposite result ; the degree at the northern extremity being found 

 equal to 60,766 fathoms, while that at the southern appeared to be 

 60,884. 



Colonel Mudge's estimate of the linear measure of a degree is made 

 by dividing the number of fathoms measured in linear extent of an arc 

 by the number of degrees and parts of a degree ascertained by ob- 

 servations of stars. Don Joseph Rodriguez has followed a different 

 course. He assumes as data the linear extent of Col. Mudge's base 

 line, and the horizontal angles of his triangles ascertained by obser- 

 vation. He assumes, also, that the figure and dimensions of the earth 

 2 F2 



