Passage adapted from Narrative of the Life of Frederick Douglass, an American Slave by Frederick Douglass (1845).

        The slaves selected to go to the Great House Farm, for the monthly allowance for themselves and their fellow-slaves, were peculiarly enthusiastic. While on their way, they would make the dense old woods, for miles around, reverberate with their wild songs, revealing at once the highest joy and the deepest sadness. [...]

     I did not, when a slave, understand the deep meaning of those rude and apparently incoherent songs. I was myself within the circle; so that I neither saw nor heard as those without might see and hear. They told a tale of woe which was then altogether beyond my feeble comprehension; they were tones loud, long, and deep; they breathed the prayer and complaint of souls boiling over with the bitterest anguish. Every tone was a testimony against slavery, and a prayer to God for deliverance from chains. The hearing of those wild notes always depressed my spirit, and filled me with ineffable sadness. I have frequently found myself in tears while hearing them. The mere recurrence to those songs, even now, afflicts me; and while I am writing these lines, an expression of feeling has already found its way down my cheek. To those songs I trace my first glimmering conception of the dehumanizing character of slavery. I can never get rid of that conception. Those songs still follow me, to deepen my hatred of slavery, and quicken my sympathies for my brethren in bonds. If any one wishes to be impressed with the soul-killing effects of slavery, let him go to Colonel Lloyd's plantation, and, on allowance-day, place himself in the deep pine woods, and there let him, in silence, analyze the sounds that shall pass through the chambers of his soul,--and if he is not thus impressed, it will only be because "there is no flesh in his obdurate heart."

        I have often been utterly astonished, since I came to the north, to find persons who could speak of the singing, among slaves, as evidence of their contentment and happiness. It is impossible to conceive of a greater mistake. Slaves sing most when they are most unhappy. The songs of the slave represent the sorrows of his heart; and he is relieved by them, only as an aching heart is relieved by its tears. At least, such is my experience. I have often sung to drown my sorrow, but seldom to express my happiness. Crying for joy, and singing for joy, were alike uncommon to me while in the jaws of slavery. The singing of a man cast away upon a desolate island might be as appropriately considered as evidence of contentment and happiness, as the singing of a slave; the songs of the one and of the other are prompted by the same emotion.

Adapted from “Greenhouses: Their Construction and Equipment” by W.J. Wright (1917)

“Generally speaking, there are only two satisfactory methods of greenhouse heating: Steam and hot water. Direct heating by stoves is not satisfactory even in small houses, and no satisfactory system has yet been devised for the use of hot-air furnaces. The only method aside from steam or hot water which deserves mention is heating by flues. They are wasteful of fuel, and their use is not justified, except in cheaply constructed houses which are used only for a few months in the spring or fall.

The principles pertaining to greenhouse heating are much the same as those involved in heating other buildings, except that the loss of heat is greater from glass than from wood or brick walls, and a higher and more constant night temperature is required than is necessary in dwellings. For this reason, relatively more radiating surface is required and boilers of larger capacity are needed.

In heating with flues the equipment consists simply of a furnace at one end of the house and a chimney at the other, the two being connected by a flue, carried underneath the bench or buried just underneath the soil, through which the heat and smoke are carried. This may be made of brick, but large-size drain or sewer tile are more commonly used. These withstand the heat and are easily and cheaply put in place. It is best to have the flue slope upward slightly toward the chimney. As has already been stated, this method is wasteful of fuel. It is also difficult to regulate. It is still employed to some extent by gardeners in cheap houses, used only in late winter or early spring for the starting of early vegetable plants, sweet potatoes, etc.”