

Corrections in a Newton' s-rings System. 



501 



Type. 



Principle employed. 



Reference. 



Smallest 

 detectable pressure. 



Bayleigh 



Tilting mercury U-tube. 



Phil. Trans. A 196, 



p. 205 (1901). 

 Auier. Journ. Sci. xiii. 



068 dyne per cm. 2 



Morley & Brush . 







June 1902. 





Threlfall 



Micrometer screw ad- 



Inst. Mech. Eng. Proc. 



0"5 dyne per cm. 2 





justments to surfaces 

 of water U-tube. 



Feb. 1904, p. 273. 



Hering 



Tilting mercury U-tube 

 with electric contacts. 



Ann. d. Phys. xxi. 1906. 



0-3 



Scheel & Heuse... 



Metal diaphragm with 

 interference fringes. 



Deutsch. Phys. Gesell. 

 Jan. 1909. 



o-i 



Chattock&Fry... 



Tilting water U-tube 

 with benzene bubble 

 indicator. 



Stanton, Proc. Inst. C. E. 

 clvi. 



Morrow, P. E. S. A 76, 



1 







1905. 

 Chattock & Tyndall, 

 Phil. Mag. xix. p. 450 



i-ooi „ 



1 



Fry 



Diapbragm. 



(1910). 

 Fry & Tyndall, Phil. 

 Mag. xxi. p. 348(1911). 



1 



' o-ooi „ 



Experiments on a manometer of this type for use at low 

 absolute pressures are now in progress. 



UniTersity of Bristol. 

 Jan. 1913. 



LIV. On certain Small Corrections in a Neicton 3 s-rings 

 System. By Allan Ferguson, B.Sc. (Lond.), Assistant 

 Lecturer in Physics in the University College of North Wales, 

 Bangor *. 



IN the progress of some experimental work w T hich demanded 

 the production and examination of a system of Newton's 

 rings formed under oblique incidence, it seemed that 

 measurements of the diameters of the rings — which, of 

 course, viewed under oblique incidence appear elliptical — 

 would furnish an accurate and easy method for the deter- 

 mination of the angle of incidence. 



For if the rings be viewed through a microscope provided 

 with independent vertical and horizontal scales, and the 



* Communicated by Professor E. Taylor Jones. 



