in Astronomy, one of the eleven planets, situated without the earth's orbit, and remarkable for the extent of its atmosphere and the redness of its light. See Astronomy Index.

The red colour of this planet, according to Dr * Supple-Brewster *, is owing to the same cause as the redness of the morning and evening clouds. When a beam of white light passes through any medium, its colour in- Astronomy, clines vol. ii. elimes to red, in proportion to the space through which it has travelled, and the density of the medium. The momentum of the red or least refrangible rays being greater than that of the violet or most refrangible rays, the former will make their way through the resisting medium, while the latter are either reflected or absorbed. The colour of the beam, therefore, when it reaches the eye, must partake of the colour of the least refrangible ray; and the redness of this colour must increase with the number of the violet rays that have been obstructed. Hence we see, that the sun, moon, and stars appear red, when in the horizon; and that every luminous object seen through a mist is of a ruddy hue.

Now, the planet Mars is allowed to have an atmosphere of great density and extent, as is manifest from the dim appearance of the fixed stars that are placed at a considerable distance from his disk. The sun's light, therefore, by which this planet is illuminated, having to pass twice through the atmosphere of Mars before it reaches the earth, must be deprived of a great proportion of the violet rays; and consequently the colour of the resulting light by which Mars is visible, must be red.

As there is a considerable difference of colour among the other planets, and likewise among the fixed stars, are we not entitled to conclude, that those in which the red colour predominates, have the greatest or the densest atmospheres? According to this principle, Saturn must have the next greatest atmosphere to that of Mars.

Pagan worship, the god of war. He was, according to some, the son of Jupiter and Juno; while others say that he was the son of Juno alone, who being displeased at Jupiter's having produced Minerva from his brain, without female aid, in revenge conceived without the assistance of the other sex, by touching a flower shown to her by Flora in the plains of Oléus, and became the mother of this formidable deity. The amours of Mars and Venus, and the manner in which Vulcan caught and exposed them to the laughter of the other gods, have been described by several of the ancient poets. He is represented as having several wives and mistresses, and a considerable number of children. He was held in the highest veneration by the Romans, both from his being the father of Romulus their founder, and from their inclination to conquest; and had magnificent temples erected to him at Rome.

Mars is usually represented in a chariot, drawn by furious horses. He is completely armed; and extends his spear with the one hand, and grasps a sword, imbrued in blood, with the other. He has a fierce and savage aspect. Discord is represented preceding his car; and Clamour, Fear, and Terror, appear in his train. The victims sacrificed to him were the wolf, the horse, the woodpecker, the vulture, and the cock.

Mars, among the older chemists, denotes iron; that metal being supposed to be under the influence of the planet Mars.

Marsais, Cesar Chesneau Du, an eminent literary character, was born at Marseilles 1676. He attached himself at an early period of life to the order of the congregation of the oratory; but the situation was too narrow for his genius, and he soon left it. At Paris he married, became advocate, and entered on this new profession with great success and approbation. Disappointed, however, in his expectations of making a speedy fortune, he abandoned the law also. About this time the peevish humour of his wife occasioned a separation. We next find him as governor to the son of the president de Maisons; and when the premature death of the father deprived him of the fruits of his industry, he engaged with the famous Law in the same capacity. After the fall of this extraordinary projector, he completed the education of the marquis de Beaufremont's children, and reared pupils worthy of his genius and industry. Although he was accused of a tendency to Deism, and though there was good reason for the accusation, yet he never infused into the minds of his scholars any principle inconsistent with sound morality, or with the Christian religion.

When he left M. de Beaufremont's family, he took a boarding house, in which, after a method of his own, he educated a certain number of young men. Unexpected circumstances obliged him to abandon this useful undertaking. He was even constrained to give some occasional lessons for the bare necessaries of life. Without fortune, without hope, and almost without resource, he was reduced to extreme indigence. In this situation he was found by the authors of the Encyclopédie, and made a partner in conducting that great work. Among many other excellent pieces, the article Grammar breathes the spirit of sound philosophy. His principles are clear and solid. He discovers an extreme knowledge of the subject, great accuracy in the rules, and great propriety in the application. M. le Comte de Lauraguais was so much affected with the distresses, and so much convinced of the merit of Du Marsais, that he procured him a pension of 1000 livres. Du Marsais died at Paris on the 11th of June 1756, in his eightieth year, after having received the sacrament. The compliment which he paid to the priest on this occasion has been considered by some as rather equivocal. But there is no necessity to deprive religion of this triumph, or philosophy of that honour which conviction and penitence must confer on it. "The faith of a great genius (says Bayle, who is entitled to credit on this subject), is not totally extinguished: It is like a spark under the ashes. Reflection and the prospect of danger call forth its exertions. There are certain situations in which philosophers are as full of anxiety and remorse as other men." Whatever were the last sentiments of Du Marsais, it cannot be denied that in the vigour of health he furnished several examples of irreligion, and to these have been added many absurd stories. The superiority of Du Marsais's talents consisted in exactness and perspicuity. His ignorance of the world, and of the customs of mankind, together with the greatest latitude in expressing whatever he thought, gave him that frank and unguarded simplicity which is often the chief ingredient of genuine humour. Fontenelle used to say of him, "that he was the most lively simpleton, and as a man of wit the most simple he ever knew." He was the Fontaine of philosophers. In consequence of this character, he was a nice judge of what was natural in every production, and a great enemy to all kind of affectation. His principal works are, 1. Exposition de la doctrine de l'Eglise Gallicane par rapport aux pretensions de la Cour de Rome, 12mo. This accurate work was begun at the desire of the pre- sident de Maisons, and did not appear till after the death of the author. 2. Exposition d'une methode raisonnée pour apprendre la langue Latine, 12mo, 1722, rare. This method appears conformable to the natural unfolding of the powers of the mind, and on that account renders the acquisition of the language less difficult; but it was liable to two great objections to vulgar and unenlightened understandings, namely, its novelty, and the censure which it conveyed against the former method. 3. Traité des tropes, 1730, 8vo; again printed in 1771, 12mo. This work is intended to explain the different significations of the same word. It is a masterpiece of logic, of accuracy, of perspicuity, and precision. The observations and the rules are illustrated by striking examples calculated to show both the use and the abuse of the rhetorical figures. It is wonderful at the same time that this excellent book had very little sale, and is scarcely known. A gentleman who wanted to compliment the author on this extraordinary performance, told him that he had heard a great deal of his Histoire des Tropes, and begged to know in what particular part of the world the nation flourished. 4. Les veritable Principes de la Grammaire raisonnée pour apprendre la langue Latine, 1729, 4to. There was only the preface of this work published, in which he introduced the greatest part of his methode raisonnée. 5. L'abecéde de la fable du Pere Jouvencet, arranged after the manner of the original plan, 1731, 12mo. 6. Une réponse manuscrite à la Critique de l'Histoire des Oracles par le Pere Baltus. There are only imperfect fragments of these papers to be found. 7. Logique, ou réflexions sur les operations de l'Esprit. This is a short tract, which nevertheless contains everything necessary to be known in the art of reasoning. It was reprinted at Paris in two parts, together with the articles which he had furnished for the Encyclopédie, 1762.