130 NOTICES OF THE MEETINGS. [ Feb. 20, 1852. 
combinations of the arcs of different circles, in which each circle 
seemed always struggling to express its own curvature, and dis- 
cordant with the sequence of the general line. 
In conclusion the lecturer said that the object of the architect 
should be to study what the Greeks and other real advancers of art 
achieved, and to extend their principles by embodying as much as 
possible the science of the day. 
It was not the curved lines or the use of the Conic Sections in 
the mouldings which produced their excellence, but because they 
pursued art in the right way; they availed themselves of whatever 
methods would obviate the optical illusions which impaired the 
beauty of their architecture, and of whatever geometrical figures 
would in the most simple manner give them the determinate varied 
curves in which they delighted. 
Several instruments for drawing curves by continued motion 
invented by the Lecturer also were exhibited: one for drawing the 
hyperbola by means of a variable triangle, with a constant base 
sliding on the asymptotes of the curve. (The same instrument would 
also draw the conchoid of Nicomedes.) An instrument on the 
principle of a skeleton cone for drawing all the conic sections — and 
an instrument for drawing the Cissoid of Diocles, with variations of 
that curve; Penrose and Bennett’s registered Helicograph for 
drawing all the varieties of the equiangular spiral from the circle to 
the straight line. A specimen of its operation was shewn in a 
drawing of an Ionic capital, after the Erechtheum ; and a simple 
instrument invented by Mr. Jopling for drawing a fine wave, or 
line of beauty, by means of the curve Jemniscata, and an oblique 
elliptic trammel, made from a pattern proposed by the same in- 
ventor. {F. C. P.] 
In the Library were exhibited : — 
Instruments used in Measuring the Parthenon; and Sketches of 
Athens, &c. by Mr. F. C. Penrose. 
“The Principles of Athenian Architecture, by F. C. Penrose, Esq.” 
Presented by the Society of Dilettanti. 
Talbotype Views of the Parthenon, Athens, &c. by Messrs. Henne- 
man and Co. 
Geometric Curves and Apparatus used in drawing them, with descrip- 
tion by Mr. Joseph Jopling. [See “An Impulse to Art; and 
Examples of Entasis,” &c. 8vo. 1849, by Mr. Jopling, presented 
by him.to the Library, R. I.] 
Specimens of Glass Mosaic, by Mr. G. H. Stevens. 
Models of Smoke-Consuming Furnaces, &c. by Messrs. Juckes, 
Addams, and Coupland. 
Model of Galloway’s Tubular Boiler. [Exhibited by Mr. Arm- 
strong. | 
Sepulchral Seals and other Antiquities, from the United Service 
Institution. : 
A Painting on Marble, by Paul Brill. [Exhibited by Mr. H. Brooke. ] 
Dies and Medals, by Mr. G. Barclay. 
