6 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



The cupola of Brunelleschi, which crowns the Duorao of 

 Florence, is an equi-clomoid. M. Hugo thinks that the the- 

 ory of the sphere has no independent existence, and that 

 it is the simple geometric corollary of the equi-domoid. 

 The passage from the pyramids of Euclid's geometry and of 

 the Egyptian architecture to the spheres of modern geometry 

 and the domes of modern architecture, M. Hugo calls the mor- 

 phology of architecture. Introd. to Descriptive Geometry. 



THE INTEGROMETER. 



The integrometer is the name of an instrument designed 

 by Deprez, a civil engineer of France, for the purpose of 

 finding the area, the curvature, the centre of gravity, and the 

 moment of inertia of any plane figure whatever, almost with- 

 out calculation ; it is an extension of the instrument known 

 as Amsler's planimeter, now extensively used by engineers 

 and draughtsmen. The instrument consists essentially of a 

 fixed ruler along which a slider can move freely: secondly, 

 of a straight rod, which is freely pivoted on the slider, and 

 which carries at one end a pointer, that is made to trace the 

 contour of the given figure ; at the other end it carries a 

 stirrup, between the prongs of which a horizontal axis ex- 

 tends with which a wheel is connected. This wheel is di- 

 vided into one hundred parts. As the pointer traces the con- 

 tour of the given figure, the wheel rolls over the plane surface 

 in a peculiar manner, such that the length of the arc through 

 which the wheel turns, multiplied by the length of the arm 

 of the rod, gives the area of the figure whose contour has 

 been traced. By a special arrangement of the instrument, 

 the centre of gravity of this contour and its moment of iner- 

 tia are also given. In short, the instrument serves to econo- 

 mize time and labor in dealing with the numerous problems 

 that occur in engineering, in relation to irregular, closed con- 

 tours. Professional Papers on Indian Engineering ',111., n.,8. 



STELLAR PARALLAXES. 



Professor Briinnow, director of the Observatory of Trinity 

 College, Dublin, has, as is well known, devoted his energies of 

 late years to the determination of the relative parallaxes of 

 the fixed stars. Many suitably placed stars have been ob- 

 served by him, and the recent Annals of the Observatory 



