unslackening

All the time he could feel his brain working ceaselessly, like a machine running with unslackening rapidity.

The Trespasser 2003

All the time he could feel his brain working ceaselessly, like a machine running with unslackening rapidity.

The Trespasser 1907

The men with whom he had had large dealings he had treated as enemies rather than friends, ever watching them covertly with close but unslackening vigilance.

A Millionaire of Yesterday 1906

On the one hand there was everything she longed for; on the other much that she disliked -- monotonous work, the loneliness of the frozen prairie in the bitter winter, the society, at very long intervals, of farmers who talked about nothing but their crops, and the unslackening strain of activity in the hot summer.

The Girl from Keller's Harold Bindloss 1905

Youth had given him all that it had to give; and though he would fain have lived on -- though no one was ever less world-weary than he -- yet in the plenitude of his exultant strength, with eye undimmed and pulse unslackening, he met the death he had voluntarily challenged, in the cause of the land he loved, and in the moment of victory.

Poems Alan Seeger 1902

Indeed the entire Old Testament is one continuous illustration of the unslackening zeal with which the wise and enlightened men of Israel -- its lawgivers, leaders, priests and prophets -- pursued their arduous and often almost hopeless task, of keeping their people pure from worships and practices which to them, who had realized the fallacy of a belief in many gods, were the most pernicious abominations.

Chaldea From the Earliest Times to the Rise of Assyria 1879

It is thus truly the unslackening spring of human progress, relaxing not even in the hour of death; but, amid the withdrawal of all the objects of present desire, carrying the soul forward in hope and triumph to other and higher regions of mental and moral development.

Theism: The Witness of Reason and Nature to an All-Wise and Beneficent Creator. 1823-1886 1855

She turned, went swiftly forward, with a straight, even, unslackening pace, which did not falter nor stop for a long, long piece of the way; _how_ long it was by the mind's measurement it would be hard to tell.

Say and Seal, Volume I Susan Warner 1852

But never presuming upon the interposition of any incident giving to France a naval ascendency upon our coast, he took his measures upon common - place principles, following the beaten tract, and fell an easy prey to his sagacious adversary; who, to prevent the interference of any occurrence impeding the progress of his views, made ready in time to take his part as circumstances might invite, and to press forward to his end with unslackening vigor.

Memoirs of the war in the Southern department of the United States 1812