348 PHILOSOPHICAL TKANSACTIOKS. [aNNO 1747. 



and no bond of iron or other metal so strong, as to keep this instrument per- 

 fectly true with respect to the earth's axis, Mr. G. has therefore devised this 

 new contrivance for a mural arch, furnished with a telescope and micrometer, to 

 be constructed so as to answer the following purposes, viz. 



1. That at any time it may appear if the plane of the instrument be vertical. 

 2. Whether a perpendicular passes exactly through the centre of the quadrant 

 and the beginning of the divisions on the limb. 3. To correct the aberration of 

 the plane of the quadrant from the vertical line, without altering the position of 

 the beginning of the divisions on the limb, with respect to the perpendicular. 

 4. And again, to correct the aberration of the beginning of those divisions, from 

 the perpendicular, without changing the proper position of the plane of the 

 quadrant with respect to the vertical line. 5. In like manner, to correct the 

 deviation of the plane of the quadrant from the plane of the meridian, without 

 altering the perpendicular situation of the plane of the quadrant, and of the 

 beginning of the divisions. 6. That it may be quite free from the variation in 

 the expansion of the metals by heat and cold. 7. That the instrument may 

 easily be rectified, viz. that it may easily appear whether the line passing from 

 the object, through the intersection of the threads in the tube to the eye, be 

 exactly parallel to the line passing through the centre of the quadrant and the 

 division shown by the rule; and to set it easily right when there is occasion; a 

 division otherwise very laborious and difficult. 



To obtain all these requisites, Mr. G. then gives a very long and minute de- 

 scription of the several parts and contrivances of this instrument, with a vast 

 multitude of references to a great number of plates and figures; in which it is 

 not now profitable to follow him, as we apprehend we are possessed of better 

 mural quadrants in this country, the description of which will hereafter occur. 



The whole quadrant itself is recommended to be of solid metal, by which 

 means, Mr. G. says, when it expands or contracts by heat or cold, it will always 

 remain similar to itself; and the free expansion or contraction will not be hin- 

 dered by its suspension. 



Two Observations relating to Morbid Anatomy . By Albert Haller, Professor 

 of Physic at Gottingen, and F. R. S. N° 483, p. 527. An Abstract from 

 the Latin. 



In the first of these observations it is stated that in a woman 40 years of age 

 the vena cava, between the origin of the left renal vein and the iliac veins, was 

 discovered to be contracted in so great a degree as scarcely to allow the blood to 

 pass through it. A portion of coagulated polypose blood was found within its 

 contracted cavity. On the other hand, the right spermatic vein was dilated to 

 such an extent, as to supply the place of the vena cava, transmitting the blood, 



