After Mr. McCabe left the school, Mr. John Seath, was appointed headmaster. His duties commenced August 11th, 1869. He was a graduate of Glasgow University and Queens of Ireland. He had taught in Brampton for five years, previous to coming here, and had good recommendations.
By this time the problem facing the school was over-crowding again. The boys of the third and fourth divisions were being taught in the Sons’ Hall. It was reported that “a thief had broken into the building and run off with the school clock, but had forgotten the key. He could have it “if he came back and asked for it.”
After the usual bickering and penny pinching, the school trustees decided that another addition would have to be built on the school. This was erected on the north-east corner and was a two story white brick structure 34 ft. by 50 ft. This made the building L-shaped when it was completed. At the point of contact of the two buildings, a forty-five foot tower was built. That made space for two cloak-rooms and two class rooms larger than those in the addition on the west side. The east wall of that part was also extended to give more space. There was a (bell) in the tower and over the years many Oshawa citizens in all walks of life, have answered its call. The alterations were completed in the fall of 1870, at a total cost of around $3000. The building was not altered again and there are many here in the city now who can remember it – the “Old Centre Street School.” The trustees decided at that time that when the population warranted it, ward schools would have to be built.
On the whole during Mr. Seath’s stay in Oshawa things went along in the school, on a fairly even keel. He reported that his assistants were co-operating well and the school was in excellent shape. He was only here two years and resigned in October 1871 to take a position in Dundas at a higher salary. He was well liked by all and there was much regret when he left. He was presented with a silver trophy inkstand on behalf of his staff and pupils.