Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led to the development of his special theory of relativity. He realized, however, that the principle of relativity could also be extended to gravitational fields, and with his subsequent theory of gravitation in 1916, he published a paper on the general theory of relativity. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. In 1917, Einstein applied the general theory of relativity to model the large-scale structure of the universe.

The present work is constructed on the same plan as my treatise on Plane Trigonometry, to which it is intended as a sequel; it contains all the propositions usually included under the head of Spherical Trigonometry, together with a large collection of examples for exercise. In the course of the work reference is made to preceding writers from whom assistance has been obtained; besides these writers I have consulted the treatises on Trigonometry by Lardner, Lefebure de Fourcy, and Snowball, and the treatise on Geometry published in the Library of Useful Knowledge. The examples have been chiefly selected from the University and College Examination Papers.

In the account of Napier’s Rules of Circular Parts an explanation has been given of a method of proof devised by Napier, which seems to have been overlooked by most modern writers on the subject. I have had the advantage of access to an unprinted Memoir on this point by the late R. L. Ellis of Trinity College; Mr Ellis had in fact rediscovered for himself Napier’s own method. For the use of this Memoir and for some valuable references on the subject I am indebted to the Dean of Ely.Considerable labour has been bestowed on the text in order to render it comprehensive and accurate, and the examples have all been carefully verified; and thus I venture to hope that the work will be found useful by Students and Teachers.

THIS work here undertaken differs somewhat in its scope and design from systems of Logic which have hitherto been given to the world. The Aristotelian Logic is simply the method of deduction and, as such, it is complete. Subsequent works, in so far as they have been strictly logical, have closely copied the great master, and have confined them-selves to an exhibition of the deductive principles and processes.

Now, the deductive method comprehends merely the laws which govern inferences or conclusions from premises previously established.
These premises may, in their turn, be inferences from other premises, and so on, to certain extent and just so far this method is all sufficient. But it is evident that the evolution of premises and conclusions, and conclusions and premises, must have limit.

The three fixed lights, or windows, subsequently exchanged for our lesser luminaries, were explained one hundred and fifty years ago to signify " the three Persons, Father, Son, Holy Ghost ; " and were used to find out the meridian, " when the sun leaves the south, and breaks in at the west window of the Lodge." While the " mossy bed," the ancient signs of disgust and recognition, as well as the primitive name of a Master Mason, are equally obscure at the present day; having been swept away, along with the original method of characterising chemical bodies by symbols, as being no longer necessary to the system.

Charles Darwin's The Origin of Species, published on 24 November 1859, is a work of scientific literature which is considered to be the foundation of evolutionary biology. Its full title was On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. For the sixth edition of 1872, the short title was changed to The Origin of Species. Darwin's book introduced the scientific theory that populations evolve over the course of generations through a process of natural selection. It presented a body of evidence that the diversity of life arose by common descent through a branching pattern of evolution. Darwin included evidence that he had gathered on the Beagle expedition in the 1830s and his subsequent findings from research, correspondence, and experimentation. Also added a Glossary on the Evolution The glossary is arranged alphabetically. Although you may find many of the terms familiar, the definitions and explanations frequently etymology..

The material contained in the following translation was given in substance by Professor Hilbert as a course of lectures on euclidean geometry at the University of G¨ottingen during the winter semester of 1898–1899. The results of his investigation were re-arranged and put into the form in which they appear here as a memorial address published in connection with the celebration at the unveiling of the Gauss-Weber monument at G¨ottingen, in June, 1899. In the French edition, which appeared soon after, Professor Hilbert made some additions, particularly in the concluding remarks, where he gave an account of the results of a recent investigation made by Dr. Dehn.

It is believed that the development of our knowledge during the last few years fully justifies this course. The theory of ionization has also been freely used, as the only means we have by which a large class of phenomena can be clearly presented and understood. It seems desirable to give some material which it is not possible to emphasize or teach thoroughly in a brief course and some things which are rather for reference than to be learned. To aid teachers and students in distinguishing such paragraphs, they are indicated by an asterisk. 

Accordingly, until other means than direct Observation of arriving at the truth were discovered, every one remained under the delusion that the Objects about us on the earth could be brought to rest absolutely freed from every motion except the celestial motion, which is consequent upon their being on a planet which rotates upon an axis, revolves in an orbit round the sun, and accompanies the solar system in its peregrinations through space.

"Why did the apple fall out of the tree? Does everything fall? What makes things fall? Can anything stop things from falling? Are the sun, moon, and stars falling? Why don't they ever hit the ground?
So many questions. Newton spent many years answering these questions by thinking and doing experiments. He made up the law of gravity. According to this law everything pulled everything else to itself by a force called gravity. How strong that force is depends on how heavy the things are and how close together..
This book telling this excellent biographic story very simple, teaching and amazingly.."

The contemplation of the various steps by which mankind has come into possession of the vast stock of mathematical knowledge can hardly fail to interest the mathematician. He takes pride in the fact that his science, more than any other, is an exact science, and that hardly anything ever done in mathematics has proved to be useless.

The chemist smiles at the childish efforts of alchemists, but the mathematician finds the geometry of the Greeks and the arithmetic of the Hindoos as useful and admirable as any research of today. He is pleased to notice that though, in course of its development, mathematics has had periods of slow growth, yet in the main it has been pre-eminently a progressive science.