will be seen that all places not more distant from the elevated pole than the given star is from the equinoctial, cannot lose its rays; whilst those within a corresponding distance of the other pole, cannot receive them. Note down those places.

1. Find those places to which the following stars never rise, and those places also where they are perpetually above the horizon.

a of Eridanus, "Achernar," (between the body of the Whale and the South Pole), 58° S. D.

Here, elevating the South Pole 58°, the wooden circle of the globe represents the terminator or boundary of the latitudes which the star's rays can reach, and I find by turning the globe, that whilst this star is always above the horizon of the southern portions of Africa, America, and New Holland, and of the whole of New Zealand, &c., it is not seen from the extreme north of Africa and Arabia; and is, of course, always absent from all Europe and the greater part of North America and Asia.

a of the Southern Fish, "Fomalhaut," (near 304 S. D.

the tail of Cetus).

B of Perseus," Algol" (in the head of Medusa) 40

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N. D.

S. D.

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a of Crux

2. How far over the North Pole can the rays of Capella, (8 of Auriga, N. D. 453,) diffuse themselves; and at what places can Capella never be seen to set?

3. How far short of the South Pole do Capella's rays reach; and from what places on our earth can Capella never be viewed?

4. If the Pole-star (a of Ursa Minor,) were exactly at the Polar point, from which part* of our earth would it never be seen?

5. The Pole-star is about 110 from the Polar point, or has a little less than 88° 27' of north declination: at what places, therefore, is it some time above the horizon, (although only at a little elevation,) besides those north of the Equator?

* i. e. disregarding the effects of refraction.



Having the declination of a star, and the place to which it is appearing to pass vertically, to find all those places to which it is at that instant rising; and what portion of the time of each diurnal rotation of our earth, certain of these places severally spend in that star's beams.

Repeat the following:

Diurnal Arc, (def. 33); Planets, (def. 1); Hour Circle, (def. 25); Sidereal day, (def. 83); Learn remaining verses of “ Rhymes on the Constellations," (Appendix.)

RULE 1. Elevate the pole to the latitude in which the star is vertical, or, which is the same thing, to the declination of the star; and bring the given place at which the star is vertical to the brass meridian. Then, the places along the western edge of the terminator will be those which are rising into that star's light.

2. Set the Index* of the hour circle to the time of the place at which the star is vertical, and give the globe its eastward rotation. It will be found that if the star be of the northern hemisphere, the southernmost place will first arrive at the eastern edge of the terminator; but that if the star be a southern one, that place most northern will first set out of its beams. Count the hours† elapsed, as each place arrives at the eastern edge of the terminator, and record them.

1. Each day, at the instant that Capella is vertical at Venice, I find that the cities of Mexico and Quito, St. Vin

*If the hour-circle be under the brass meridian, it is to be turned until the graduated edge of the brass meridian cuts the hour.

The hours must be counted, especially if the hour-circle have only one row of figures.



cent, (near the bay of the Virgin, N. of California,) and the Isle of St. Francisco, (north of the Island of St. Catherina, east coast of South America,) are rising into its beams. Supposing it to be 10 o'clock at Venice, in how many hours, from that time, will these several places set out of Capella's beams?

Here, elevating the North Pole to 45°, (i. e. to the latitude of Venice), I bring Venice to the brass meridian, and set the hour circle to 10, the time given: All places now above the wooden circle, or terminator, have Capella above the horizon. Keeping the globe steady, I seek along the western edge of the terminator, and note down, the principal places rising into Capella's light, of which places, it is evident, that since Capella is a northern star, St. Francisco, the place most south, will first have passed through its beams. Next, turning the globe eastward, I find that when St. Francisco has arrived at the eastern edge of the terminator, to have Capella setting in the west, the index has traversed about 7 hours; but that Quito is not in this condition until about 12 hours have passed-Mexico, after somewhat more time-St. Vincent, California, after much more time, &c. These portions of time are to be given.

2. [June 20th, 12 at night], v of Draco, (Etanin) 51° N. D. is vertical at Blackheath: What places are at that instant rising into its rays; and of these places, what several portions of time do Chatham Isle (one of the Galapagos), Cuzco (Peru), the Island of St. Catherina, and the Island of Tristan de Conha, daily spend in those rays?

3. On 25th March, "Antares" (a of Scorpio) is vertical to Cape St. Mary (S. point of Madagascar), at 11 o'clock at night: to what places is it rising; and of these places, how long will the following, severally, have it above their horizon? viz. Anglesea, St. Mary's (East I. of the Azores), and the south point of the Island of Chiloe (S. of Chili).

4. When 8 of Orion's Girdle is vertical to the Galapagos at a certain hour, (say 1 o'clock in the morning), it is rising to the following places :-Tanaga, (one of the Aleouskie Islands); Isle of St. Pierre, (11° N. lat.); the Feejee Islands; Cape E. New Zealand: How much of the sidereal day do they severally spend in its beams?

5. On 3rd May, 1840, the beautiful planet Jupiter will be in the zenith of any place 15° south when it is midnight at that place. What places will be rising into its beams when it is vertical just north-east of Otaheite; and of

these places, how long will the following severally continue in his light? viz. Cape Elizabeth, (the N. point of Saghalien,) Great Lekeyo, (Loo Choo Isles); N. E. point of Celebes, (adjoining the Sea of Celebes); and Sandy Point, or north-west Cape, (westernmost of New Holland).

6. When 7 of "Crux" is vertical to Cape Horn, 28th Sept. at noon, or on any other day at any other time, it is rising to the following places :- Savannah River; Bay of St. Magdalena, (S. W. of California); Christmas Isle, (a little north of the Equator); the principal of the Feejees; Erronan, or Erromango,* (south Island of the New Hebrides); Glass-House Bay, (New Holland); Nuyt's Islands, (S. coast of New Holland). What are the diurnal arcs of this star at these several places?



Remark. It is hoped that the pupil will now have ceived, that what is called the "rising" and "setting" of a heavenly body, and its daily westward course, are occasioned solely by the eastward revolution of our earth about its axis. The portion of time occupied by this apparently westward passage of a heavenly body, and which is called its "Diurnal Arc," varying in any certain latitude with the declination of the star; or, in the case of any certain star, with the latitude of the place; but being, invariably, 12 hours for every star to the inhabitants of the Equator, and twelve hours at every place if the star is in the Equinoctial. The apparent altitude of any heavenly body, or its elevation above the horizon of any place, at any certain time after its rising, is, in like manner, dependent upon latitude and declination; and, corresponding exactly with the elevation of that place in its light, may thus be found for any

*It was by the inhabitants of this island, that the devoted Missionary, Williams, was killed, 22nd November, 1839.



hour by the Terrestrial Globe, if the time of the star's rising, &c., be known.


Having the declination of a star, to find at what altitude the star appears to the inhabitants of a given place, after the lapse of a certain portion of time from its rising.

Repeat the following:

Complement, (N p. 2); Sensible Horizon, (def. 27); Rational Horizon, (def. 28); Zenith distance, (def. 40); Altitude, (def. 44) ; Repeat" Rhymes on the Constellations," (Appendix).

RULE.-Elevate the pole to the North or South declina. tion of the star, to exhibit the latitudes of the surface which rise into its light: bring the given place to coincide with the western edge of the terminator, and set the index of the hour circle to any hour, as a mark. Next, turn the globe eastward until the index have passed over the portion of time given; and the elevation of the proposed place above the terminator, will be the altitude at which the star appears above the horizon. Find these degrees of elevation, by attaching the quadrant of altitude to the declination of the star in the zenith of the brass meridian, and making its graduated edge pass across the place.

Since the quadrant of altitude is thus attached to the zenith of the place where the star is vertical, its pivot may represent the star; and the number of degrees between this pivot and the given place, shows the zenith distance of the star.

1. At what altitude does Arcturus (Dec. 20, N.) appear above the horizon of London, an hour and a half after it has risen?

Here elevating the North pole 20°, I bring London to the western edge of the terminator; then, setting the hour-circle and turning the globe until the index has traversed 1 hour, I find by the quadrant that London is degrees above the terminator.

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