17 
sphere, but repelled by one another. The lecturer illustrated this 
by floating a number of magnetized needles through pieces of 
cork in a vessel of water. The needles were placed vertically, 
with similar poles similarly directed. They therefore repelled one 
another, but were all attracted towards a centre by a magnet 
placed under the vessel. It was shown that, under these circum- 
stances, when the number of needles was few they took up positions 
in a ring; but that as the number was increased, successive rings 
were formed inside one another. In asimilar way Sir J. J. Thomson 
supposes the structure of the atom, upon which the chemical 
properties depend, to pass through successive periods as the number 
of electrons contained, and thereby the weight of the atom, is 
increased. 
Dr. Wilson finally showed by experiment that a flame discharges 
negatively charged particles towards a positively charged body. 
Friday, March 5th. Dr. F. Womack, M.B., B.Sc., in the chair. 
Mr. Percy J. Harding, M.A., gave a lecture entitled ‘* Division 
according to Cocker; a Chapter from the History of 
Arithmetic,” illustrated with lantern slides. Edward Cocker, 
the lecturer said, was a professional writing master, who lived in 
the seventeenth century, during the times of Cromwell and Charles 
Il. He added arithmetic to the subject of writing, as was customary 
in those days. He is interesting as having first made popular our 
present day method of working long division sums. Portraits of 
him were thrown on the screen. Writing was not a common 
accomplishment in those days, being confined almost entirely to 
the clergy. When the unlearned class took to writing, it was 
taught in a very serious manner by men who made a speciality 
of it. Arithmetic was generally taught by the same men for the 
sake of convenience. On the other hand, the better educated class 
confined themselves mostly to the classics and never learned 
_ arithmetic, considering it suitable only for business men. 
Ki 
i 
The lecturer then gave an account of the way in which the 
practice of arithmetic spread from the East into Europe. The 
_ Hindoos had much the same method in use as we have now. They 
had symbols, probably derived from the Sanskrit, to indicate the 
different numbers, and they worked on the decimal system. A 
most important invention which we owe to them is the cipher 
_ to denote “nothing.” This gradually spread through the Persians 
_ and Arabians, following the course of the development of commerce, 
_ into Italy. It is said to have been introduced by Leonard of 
Pisa in 1202. Meantime, in Europe, the usual way of calculating 
B 
