—­Mill:  The Realm of Nature. (Copyright, 1892, by Charles Scribner’s Sons.)

EXERCISES

A. In your reading, notice how often the effects are indicated by the use of some one of the following expressions:  as a result, accordingly, consequently, for, hence, so, so that, thus.

B. Which sentences state causes and which state effects in the following paragraphs?

1.  The power of water to dissolve most minerals increases with its temperature and the amount of gases it contains.  Percolating water at great depths, therefore, generally dissolves more mineral matter than it can hold in solution when it reaches the surface, where it cools, and, being relieved of pressure, much of its carbonic acid gas escapes to the atmosphere or is absorbed by aquatic plants or mosses.  Hence, deep-seated springs are usually surrounded by a deposit of the minerals with which the water is impregnated.  Sometimes this deposit may even form large hills; sometimes it forms a mound around the spring, over the sides of which the water falls, while the spray, evaporating from surrounding objects, leaves them also incrusted with a mineral deposit.  Percolating water evaporating on the sides and roof of limestone caverns, leaves the walls incrusted with carbonate of lime in beautiful masses of crystals.  Water slowly evaporating as it drips from the roof of caverns to the floor beneath leaves a deposit on both places, which gradually grows downward from the roof as a stalactite, and upward from the floor as a stalagmite, until these meet and form one continuous column of stone.

—­Hinman:  Eclectic Physical Geography.

2.  The frequent use of cigars or cigarettes by the young seriously affects the quality of the blood.  The red blood corpuscles are not fully developed and charged with their normal supply of life-giving oxygen.  This causes paleness of the skin, often noticed in the face of the young smoker.  Palpitation of the heart is also a common result, followed by permanent weakness, so that the whole system is enfeebled, and mental vigor is impaired as well as physical strength.  Observant teachers can usually tell which of the boys under their care are addicted to smoking, simply by the comparative inferiority of their appearance, and by their intellectual and bodily indolence and feebleness.  After full maturity is attained the evil effects of commencing the use of tobacco are less apparent; but competent physicians assert that it cannot be safely used by those under the age of forty.

—­Macy-Norris:  Physiology for High Schools.