us to observe uniformity in this respect but go to nature for your facts. Write what you see, and it may even be that you will write something of intrinsic worth, for not everything has yet been seen. Write what you see for yourself: thus only will your work be interesting, thus only will it bear the impress of sincerity and conviction, and come to have authority among men.

Of

The following outline is extracted from Bauerman's Descriptive Mineralogy and will suggest a method of procedure for the description of other minerals. course in writing an essay, this abbreviated catalogue style must not be used. Let every sentence be complete in itself and let them all be connected as smoothly as possible.

DIAMOND.

Form and Structure. — Crystals cubic; with brilliant faces faces pitted; faces striated or curved; transparent, translucent. Lustre, adamantine. Colorless, or in tints of gray, yellow, brown, pink, or blue, the latter being the rarest. Refractive. Strong chromatic dispersion, causing a brilliant play of colors when faceted. Becomes positively electric by friction; often phosphorescent after exposure to sunlight.

Composition. -Carbon, with minute traces of foreign sub

stances. Infusible.

Occurrence and Distribution.Found in Brazil, the Ural, India, Australia, Borneo, and South Africa; the first and last localities, especially the latter, being the most productive at present. In South Africa the productive localities are the gravels of the Vaal and Orange rivers, and more particularly dykes or pipes of decomposing igneous rocks penetrating schists. These have now been worked several hundred feet below the surface without getting to undecomposed rock. The diamonds are found irregularly interspersed through it, and may be an original constituent, but

the general opinion of local investigators is that they have been derived from older rocks below.

The largest known diamond is said to be in Borneo, and to weight 367 carats or 1284 Troy grains. The Pitt, a cut brilliant, is of 136 carats. The Koh-i-Noor in the original oriental shape was 186, but has been reduced to a brilliant of 124 carats. Many large crystals have been discovered of late years in South Africa.

Use. The chief use of diamond is for ornamental purposes, the crystals being reduced by cutting or grinding with diamond dust upon a lapidary's wheel to a double pyramidal form, unsymmetrical to the base, being pointed at one end, and with a large flat surface at the other, as in hemimorphic crystals. The pyramid is cut with the largest number of faces possible, to obtain a maximum of total reflecting surfaces; the stone is mounted with the flat surface uppermost. These are known as brilliants, and can only be obtained from well-shaped crystals. Those of less regular form are cut as roses, in which the surface is covered with triangular facets, and the thinnest twins or flat cleavage pieces are made into tables, having only a narrow band of facets on the sides. Diamonds that, from want of lustre or defects, cannot be cut, are called Bort. For glass-cutting the apex of an octahedral crystal is required, so as to have a solid point, a cleavage fragment or other splinter being only useful for writing or scratching.

The object here again is to describe what takes place. The problem is analogous to that of Exercise XXIV., the difference being that here we deal with natural instead of artificial processes. Select a subject, if possible, upon which you can write partially at least from first-hand knowledge. Watch the processes of inorganic nature; examine snow crystals, watch the formation of ice, the erosion of rocks by the waters of a creek, the sedimentary deposits in the creek's bed. Or material may be obtained from simple experiments, such as suspending a string in a solution of sugar, as in the manufacture of rock-candy, or "crystallizing" grasses by dipping them in a solution of salt or alum. Then supplement your own knowledge by recourse to books on chemistry, mineralogy, and geology; for example, Bauerman's Descriptive Mineralogy, Dana's Manual of Geology, Shaler's First Book in Geology, Winchell's Walks and Talks in the Geological Field, Sparks from a Geologist's Hammer, Geological Excursions, and Geological Studies.

The following extract, from a chapter on the Application of the Observational Method in Teaching, in Alexander Winchell's Shall We Teach Geology? will afford many hints for the gathering of material for this kind of composition-writing. Professor Winchell supposes the student to be in "a quarry region, as at Potsdam, N. Y., Portland, Conn., Berea, O., Joliet, Ill.”

You notice that the rocks which these workmen are quarrying lie in beds or layers. Each of these is a stratum. The separation between one stratum and another is generally a very narrow fissure or joint. Often, however, you find the joint filled with some other kind of material. This is a seam. Sometimes the seam is of an

earthy or clayey character. Sometimes one stratum is so closely joined to another that one can scarcely say there exists either seam or joint. Observe all this for yourself. Generally you find several strata in immediate succession much alike. Do you see them so here? Or do you find a decided contrast of two adjoining strata? In what does the contrast consist? Are they of different color? Of different fineness? Of different degrees of homogeneity, or likeness of substance from side to side? Can you detect any lines running along the broken edges of any of the strata? What are they due to? What renders them visible and distinguishable? These are lines of lamination. If we have a sandstone here, perhaps we shall find some laminæ running obliquely across the broken edges of certain strata. This is oblique lamination. Look at some of these blocks which have been quarried; tell me which was the upper side. How does the upper differ from the lower side? Do these strata lie in a horizontal position? Does the upper surface present any inclination ? What angle does it make with a horizontal plane? Is it five degrees? Is it twenty degrees? This angle is the dip of the stratum. Here is an angle of ninety degrees between this horizontal and this perpendicular line. Half of this is an angle of forty five-degrees; and half of this is an angle of twenty-two and one-half degrees. Represent such an angle. Represent an angle of eleven degrees. Toward what direction does this stratum dip? It is southwest, perhaps. Then the strike is northwest and southeast. How thick is this stratum? Measure it with a rule. How thick is the next one? Come to the wall of the quarry and measure its entire height. Sit down and make a sketch of this wall. Distinguish each stratum exactly as it is. Preserve their proportional thicknesses. Describe each stratum separately, beginning at the bottom. Let the strata be designated A, B, C, D, etc. In describing, give kind of rock, color, texture, solidity, purity or impurity, homogeneity or want of it, thickness. State which stratum is best adapted to the uses to which the stone is applied. As bearing on the uses, you may take a fragment home and weigh it in its natural condition then weigh it after drying as completely as you have means for. If you have no balance, go to the apothecary, or omit this experiment. Then also with reference to use, you may observe whether

the stone wears away much on surfaces exposed to the weather. Does it weather smooth? Does it weather into concave depressions? Do fissures appear in it? Does it develop rusty specks or blotches? If so, these are probably caused by iron in it.

Many subjects will readily occur, any one of which will offer material for a description of considerable length. Keep in mind what is wanted, and keep in mind the injunction to rely on your own observation. Avoid the style and method that have been so prevalent in juvenile compositions of this class, in which the writer begins, "There are a great many kinds of apples, such as the Snow-apple, the Winesap, the Bellflower, etc.," and then wanders off in the second sentence to some statement about the uses of apples, and in the third to something entirely different still. Such compositions are mere collections of detached thoughts, 'without unity or symmetry, alike uninteresting and unprofitable. Remember that what we want now is chiefly description. And if you have chosen to describe an apple, what you want first is not pen and ink and paper but an apple, and, if you cannot break it, a knife to cut it. Then proceed in a methodical way.

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