The Astronomy of Milton's 'Paradise Lost' by Thomas Nathaniel Orchard (easy books to read in english TXT) 📕

We can imagine that Galileo’s astronomical views, which at that time were the subject of much discussion among scientific men and professors of religion, and on account of which he suffered persecution, were eagerly discussed. It is also probable that the information communicated by Galileo, or by some of his followers, may have persuaded Milton to entertain a more favourable opinion of the Copernican theory. The interesting discoveries made by Galileo with his telescope without doubt formed a pleasant subject of conversation, and Milton enjoyed the privilege of listening to a detailed description of these from the lips of the aged astronomer. The telescope, its principle, its mechanism, and the method of observing, were most probably explained to him; and we can believe that an opportunity was afforded him of examining those in Galileo’s observatory, and of perhaps testing their magnifying power upon some celestial object favourably situated for observation. Though Milton has not favoured us with any details of his visit to Galileo, yet it was one which made a lasting impression upon his mind, and was never afterwards forgotten by him. ‘There it was,’ he writes, ‘I found and visited the famous Galileo, grown old, a prisoner of the Inquisition for thinking in astronomy otherwise than the Franciscan and Dominican licensers thought.’ In years long after, when Milton, himself feeble and blind, sat down to compose his ‘Paradise Lost,’ the remembrance of the Tuscan artist and his telescope was still fresh in his memory.

By the invention of the telescope and its application to astronomical research, a vast amount of information and additional detail have been learned regarding the bodies which enter into the formation of the solar system; and by its aid many new ones were also discovered. On sweeping the heavens with the instrument, the illimitable extent of the sidereal universe became apparent, and numberless objects of interest were brought within the range of vision the existence of which had not been previously imagined.

The Galilean telescope was invented in 1609. But the magnifying power of certain lenses, and their combination in producing singular visual effects, are alluded to in the writings of several early authors. The value of single lenses as an aid to sight had been long known, and spectacles were in common use in the fourteenth century. Several mathematicians have described the wonderful optical results obtained from glasses concave and convex, of parabolic and circular forms, and from ‘perspective glasses,’ in which were embodied the principle of the telescope. It is asserted that our countryman, Roger Bacon (1214), had some notion of the properties of the telescope; but among those familiar with the combination of lenses the two men who made the nearest approach to the invention of the instrument were Baptista Porta and Gerolamo Fracastro. The latter, who died in 1553, writes as follows: ‘For which reason those things which are seen at the bottom of water appear greater than those which are at the top; and if anyone look through two eye-glasses, one placed upon the other, he will see everything much larger and nearer.’ It is doubtful if Fracastro had any notion of constructing a mechanism which might answer the purpose of a telescopic tube. Baptista Porta (1611) is more explicit in what he describes. He writes: ‘Concave lenses show distant objects most clearly, convex those which are nearer; whence they may be used to assist the sight. With a concave glass distant objects will be seen, small, but distinct; with a convex one, those near at hand, larger, but confused; if you know rightly how to combine one of each sort, you will see both far and near objects larger and clearer.’ He then goes on to say: ‘I shall now endeavour to show in what manner we may continue to recognise our friends at the distance of several miles, and how those of weak sight may read the most minute letters from a distance. It is an invention of great utility, and grounded on optical principles; nor is at all difficult of execution; but it must be so divulged as not to be understood by the vulgar, and yet be clear to the sharp-sighted.’ After this, he proceeds to describe a mechanism the details of which are confusing and unintelligible, nor did it appear to bear any resemblance to a telescopic tube.

In a work published by Thomas Digges in 1591, he makes the following allusion to his father’s experiments with the lenses: ‘My father, by his continuall painfull practices, assisted with demonstrations mathematicall, was able, and sundry times hath by proportionall glasses, duely situate in convenient angles, not only discouered things farre off, read letters, numbered peeces of money with the verye coyne and superscription thereof cast by some of his freends of purpose, upon downes in open fields; but also seuen miles off, declared what hath beene doone at that instant in priuate places.’ It must be admitted that if Leonard Digges had not constructed a telescope, he knew how to combine lenses by the aid of which a visual effect was created similar to that produced by the use of the instrument.

The inventor of the telescope was a Dutchman named Hans Lippershey, who carried on the business of a spectacle-maker in the town of Middelburg. His discovery was purely accidental. It is said that the instrument—which was directed towards a weather-cock on a church spire, of which it gave a large and inverted image—was for some time exhibited in his shop as a curiosity before its importance was recognised. The Marquis Spinola, happening to see this philosophical toy, purchased it, and presented it to Prince Maurice of Nassau, who imagined it might be of service for the purpose of military reconnoitring. The value of the invention was, however, soon realised, and in the following year telescopes were sold in Paris. In 1609, Galileo, when on a visit to a friend at Venice, received intelligence of the invention of an instrument by a Dutch optician which possessed the power of causing distant objects to appear much nearer than when observed by ordinary vision. The accuracy of this information was confirmed by letters which he received from Paris; and this general report, Galileo asserted, was all he knew of the subject. Fuccarius, in a disparaging letter, says that one of the Dutch telescopes had been brought to Venice, and that he himself had seen it. This statement is not incompatible with Galileo’s affirmation that he had not seen the original instrument, and knew no more about it than what had been communicated to him in the letters from the French capital. It was insinuated by Fuccarius that Galileo had seen the telescope at Venice, but, as he denied this, we should not hesitate to believe in his veracity.

Immediately after his return to Padua, Galileo began to think how he might be able to contrive an instrument with properties similar to the one of which he had been informed; and in the following words describes the process of reasoning by which he arrived at a successful result: ‘I argued in the following manner. The contrivance consists either of one glass or of more—one is not sufficient, since it must be either convex, concave, or plane. The last does not produce any sensible alteration in objects; the concave diminishes them. It is true that the convex magnifies, but it renders them confused and indistinct; consequently, one glass is insufficient to produce the desired effect. Proceeding to consider two glasses, and bearing in mind that the plane causes no change, I determined that the instrument could not consist of the combination of a plane glass with either of the other two. I therefore applied myself to make experiments on combinations of the two other kinds, and thus obtained that of which I was in search.’ Galileo’s telescope consisted of two lenses—one plano-convex, the other plano-concave, the latter being held next the eye. These he fixed