368 Cambridge Philosophical Society. 



February 3. — 1 . A model and description of an improved Carriage Drag^, 

 By Robert Russell, mill-wriglit, Denny, Loanhead. 

 \ 2. A description and drawing of a new Cross-cutting Saw. By Dixon 

 Valla NCE, Libberton, Lanarkshire. 



3. A description and drawing of an improved Indicator for steam en- 

 gines, and of an Oil Test. By John M'Naught, engineer, Robertson 

 Street, Broomielaw, Glasgow. 



4. A model, drawings, and description of a Horizontal Air Pump. By 

 John MTlkish, Esq. Maryfield, Edinburgh, M. S. A. 



Mr Robert Kirkwood, engraver, was admitted an Ordinary Member. 

 February 17 — 1. A model, drawing, and description of a new Iron 

 Bridge. By Adam Wilson, smith. Mint, Edinburgh. 



2. A model and description of Safety Windows for upper stories of 

 houses. By Thomas Johnston, ink manufacturer, Glasgow. 



3. A description and engraving, and directio)is for using an Extinguisher 

 for females' dress on fire. By Thomas Johnston, ink manufacturer, 

 Glasgow. 



Henry Tod, Esq. W. S. was admitted an Ordinary Member. 



3. Proceedings of the Cambridge Philosophical Society. 



February 92, 1830. — The Rev. Professor Parish, one of the Vice-Presi- 

 dents, being in the chair, 



A paper was read by J. Challis, Esq. of Trinity College, on the inte- 

 gration which on certain suppositions can be effected of the general equa- 

 tions of the motion of fluids ; and on the application of the results to the 

 solution of various problems. Among other cases Mr Challis considered 

 that of a stream of air issuing through an orifice in a plane, and flowing 

 against a plate placed near to the orifice. It appears that the theory 

 gives in this instance a pressure urging the plate towards the plane, such 

 as is found to exist by experiment. 



A paper was also read by the Rev. L. Jenyns, on the Natter-Jack (Bufo 

 rubeta) of Pennant, containing an account of its habits, collected from the 

 observations of several individuals of the species during a period of two 

 months; and to these notices was added an enumeration of the Reptiles 

 found in Cambridgeshire. 



After the meeting. Professor Henslow gave an account of the discoveries 

 recently made with respect to endosmose and exosmose ; and of the appli- 

 cation of these principles to the explanation of the motion of the sap in 

 plants; with some considerations on the theory for the explanation of 

 these phenomena proposed by M. Poisson. 



March 8. — A communication from the Rev. C. P. N. Wilton of St John's 

 College, was read, containing an account of a visit to Mount Wingen, a 

 burning mountain in Australia. See this No. p. 270. 



Mr Coddington explained the principle of a microscope of a new and 

 simple construction, which had been made according to his directions by 

 Mr Cary, and which he exhibited to the Society. 



After the meeting Professor Airy gave an account, illustrated by models, 

 of the instruments which have been used at different periods, and in diffe- 

 rent countries, for the purpose of measuring the altitudes of stars. He de- 



