When North America proposed a competition for the construction of a tower to be erected at the Universal Exposition of 1892, a Spanish architect, a native of Bilboa, Mr. M. Alberto de Palacio, drew an original de-sign, of which we publish an engraving.

Mr. De Palacio has conceived a most perfect form, the sphere, which could not have been used prior to the knowledge of iron as a building material, because only by the modern methods of uniting the various parts, of which this material is susceptible, could a sphere be produced with a diameter of nearly 1,000 feet, that is, equal to the height of the Eiffel tower. This idea symbolizes the geographical completion of the earth which was realized by Christopher Columbus' discovery of the New World.

The following is a description of the magnificent design : The colossal sphere is mounted on a base which is 262 feet high, and is crowned at its North Pole by the caravel which carried Columbus to the New World. The monument is brilliant with the colors of the continents, oceans and islands of the terrestrial sphere.

The sphere will be encircled at the equator by a platform 3 280 feet, or more than half a mile, long. An exterior spiral running around the northern hemisphere will form a track nearly two miles long, leading from the equator to the North Pole. At night the sphere will be illuminated by the lines of light which will form the outlines of the continents and islands, thus casting over the city torrents of refulgent brilliancy. The great pyramids of Egypt, the Sphinx, and the Colossus could lie in the hollow interior like jewels in their case. So much for the exterior aspect.

An interior track runs around the southern hemisphere from the South Pole to the Equator, where it joins the exterior spiral. The total length of the spiral is nearly four miles, over which the sightseer can travel on a tramway.

In the base and under the majestic central rotunda will be placed a gigantic statue of the great discoverer surrounded by the navigators and missionaries who rendered his discovery fruitful. In the semicircle around this Olympus of heroes, inclosing the amphitheater, will be allegorical statues representing all the Spanish nations.

In the remaining spaces of the compartments in the base a large Columbus library will be distributed ; auditorium for the cultivation of the natural sciences, museums of zoology, mineralogy, and botany of America, rooms for the Spanish Geographical Society, a great naval museum in the interior central compartment, a meteorological observatory in the hull of the caravel. All this is independent of the promenades, cafes, and restaurants for the public.

In the interior the celestial sphere can be exactly reproduced. It can also be used for magnificent panoramas, because the spherical form is the best for obtaining illusions of perspective. There will be a place for public entertainments.

This astonishing monument can serve as a perennial remembrance of the first Spanish-American and Colonial Exposition.

Mr. Palacio secures the stability of this immense mass by means of a simple method similar to that used for equestrian statues, so that the sphere will be able to resist winds of greater force than a cyclone.

From a business point of view Mr. Palacio makes the following calculation :

One hundred thousand spectators paying an entrance fee of $1, will bring $100,000. This will replace the capital in 62 days, without counting the profits of the cafes, entertainments, etc. The estimated total cost is $6,000,000.

INDISPENSABLE DATA FOR THE ESTIMATE.

Diameter of the sphere.........................................984 ft.

Elevation of the sphere above the ground.......................262 "

Total height of the monument.................................1,312 "

Surface of the sphere......................................337,989 sq. yd.

Volume..................................................18,492,341

Length of the equatorial platform............................3,280 ft.

Length of the ascending spiral..............................19,684 "

Total pressure of the wind of a

hurricane against the monument.......................42,390,00 lbs.

ESTIMATE.

Cost of the sphere and its base.........................$5,059,200

Cost of the machinery, elevators and other accessories..$1,240,000