He was an active member of the Chapman-Hall meeting in Boston, which organized the Republican party in Massachusetts, with which party he has ever been in full accord. In 1852 he was a member of the electoral college of Massachusetts, which gave the vote of the state for Gen. Winfield Scott; and also a member of the college of 1864, which gave the vote of the state for Gen. Ulysses S. Grant. He was a delegate from the sixth district of Massachusetts to the Chicago convention which nominated Abraham Lincoln for president in 1860. In 1858 and 1859, he was a member of the executive council of Massachusetts, with Nathaniel P. Banks as governor. In 1862 he was appointed, by President Lincoln, collector of internal revenue for the sixth district of Massachusetts. After holding this office for four years, he was removed by President Johnson, without cause; but was again appointed to the same office by President Grant, in 1870, which position he held until 1875, when this district was consolidated with two other districts. This was one of the largest and most important paying districts in the country, and under the administration of Dr. Cogswell its affairs were conducted with marked efficiency, and with absolute correctness. Dr. Cogswell has always taken a deep interest in educational matters, and he has given some of his best service to the management of important schools. He has been, for a long time, a trustee of Atkinson Academy, and is also a trustee of the Peabody Academy of Science, in Salem, Mass. But the crowning work of his life in the department of education has been in connection with Bradford Academy. For nearly fifty years he has been a trustee of this famous school, and during most of this time has had the entire management of its financial affairs. His efficiency in this work is best illustrated by the success of the school in all its departments. The splendid appointments of this academy for the higher education of young ladies, the ample grounds, the perfection of the school edifice, the excellence of the teachers, and the scope of its curriculum, give it a prominence and a power not excelled by any similar institution in the land. It may be safely estimated that Dr. Cogswell, by his long connection with this, the oldest school for young ladies in the country, has had a wider personal experience in matters of internal management, in consultation with teachers, and in advising with reference to pupils, than any man connected with an institution of this character; and he has the pleasure, with his associate trustees, of seeing this school, by the generosity and interest of its many friends, placed upon an enduring foundation. He was elected, in 1869, a member of the American Association for the Advancement of Science, and is also a member of the New England Historic-Genealogical Society.