In the case of a single lens of glass with the most favourable curvatures, Sf is about equal to a 2 f, so that a 4 must not exceed off.
Hence impossibly deep curvatures would be required for such a triple objective of any normal focal length.
The signs of p p are to be taken positive when the curvatures are as in the /~ standard case shown in fig.
He thus showed that at a curved part of the surface, a superficial particle would be urged towards the centre of curvature of the surface, and he gave reasons for concluding that this force is proportional to the sum of the curvatures of the surface in two normal planes at right angles to each other.
Even If The Tension At The Circumference Of The Tube Acted Vertically, And The Whole Of The Liquid Below This Level Passed Into The Drop, The Calculation Would Still Be Vitiated By The Assumption That The Internal Pressure At The Level In Question Is Atmospheric. It Would Be Necessary To Consider The Curvatures Of The Fluid Surface At The Edge Of Attachment.