55 
Ordinary Meeting, December^ 14th, 1875. 
Edward Schunck, Ph.D., F.R.S., &c., President, in the 
Chair. 
Professor Schorlemmer exhibited a sample of peat from 
lagoons in the Sierra Madre in Mexico. It is very dense 
and not readily inflammable, giving very little flame, but 
when once red-hot it burns completely, without requiring 
much draught, to a perfectly v/hite ash containing much 
calcium carbonate and a little sodium sulphide, which is 
derived from glauber salt which the peat contains. 
“On Graphic Methods of Solving Practical Problems” by 
Professor Osborne Reynolds, M.A. 
In the first part of this paper it is pointed out that, when 
dealing with practical problems by the aid of the graphic 
method, it is not necessary to break off the operations of 
drawing, and find numerical values for the quantities repre- 
sented, in order to perform on them the operations of multi- 
plication and division. For by the aid of a parallel ruler 
the operations of multiplication and division may be per- 
formed graphically with great facility. The only geometri- 
cal proposition involved being that of finding a fourth 
proportional to three distances. When two distances have 
to be multiplied or divided the one by the other, a third dis- 
tance is chosen equal to unity, and a fourth proportional 
found which represents the product or ratio of the first 
according as unity is the first or third of tlie given quanti- 
ties. 
^ The method was illustrated as applied to the determina- 
tion of areas, centres of gravity, and moments of inertia. 
In the second part of the paper a graphic method is 
described by which the velocity and acceleration of a 
moving point can be determined wlien the times at which it 
Peoceedings-Ht. & Phil. Soc.-Vol. XV.-No. 4.-Session 1875-6. 
