▁MA ▁▁ 1 9 6 8 - 1 9 6 9 ▁Arthur ▁Ernest ▁B rom field , ▁MA ▁▁ 1 9 6 9 - 1 9 7 1 ▁David ▁William ▁Alexander ▁Donald , ▁O BE ▁T D ▁▁ 1 9 7 1 - 1 9 7 3 ▁John ▁Young ▁▁ 1 9 7 3 - 1 9 7 5 ▁John ▁Gall ow ay ▁Wal lace , ▁O BE ▁MA ▁▁ 1 9 7 5 - 1 9 7 7 ▁Max well ▁Douglas ▁Thor nt on ▁▁ 1 9 7 7 - 1 9 7 9 ▁Robert ▁E ad ie ▁Mac don ald , ▁MA ▁▁ 1 9 7 9 - 1 9 8 1 ▁David ▁Douglas ▁M ck inn on , ▁B Sc ▁F IMA ▁▁ 1 9 8 1 - 1 9 8 3 ▁George ▁David ▁G w ilt , ▁MA ▁▁ 1 9 8 3 - 1 9 8 5 ▁Alexander ▁Den is ▁Sh ed den , ▁B Sc ▁F SA ▁▁ 1 9 8 5 - 1 9 8 7 ▁John ▁M ait land ▁Mach arg , ▁MA ▁▁ 1 9 8 7 - 1 9 8 9 ▁William ▁Mor r ison ▁Mor r ison , ▁MA ▁▁ 1 9 8 9 - 1 9 9 0 ▁James ▁Mc g ill ▁S oun ess ▁▁ 1 9 9 0 - 1 9 9 2 ▁Al ist air ▁Ne ill , ▁MA ▁MS ▁F P MI ▁FC II ▁▁ 1 9 9 2 - 1 9 9 4 ▁John ▁Joseph ▁M