The slow emergence of Dalton's chemical atomic theory has long been a considerable puzzle to historians of science The lengthy delay between Dalton's early work on mixed gases (September 1801) and particle weights (September 1803) and the eventual publication of the first part of his New System of Chemical Philosophy (June 1808) has called forth a variety of explanations. It is now more than half a century since A. N. Meldrum stressed

“…the efforts Dalton had to make, in order to arouse attention to the importance of his ideas regarding atoms. For some nine years (1801-1810), if not longer, he endeavoured to spread abroad his ideas, both by private communications and publicly, by his writings and by lectures in various parts of the country…

“Dalton's chemical theory was formed by the 6th September 1803, and he proceeded forthwith to extend and apply it, and make it known in every direction…”

And though Meldrum's view is now no longer accepted, no systematic and detailed account of Dalton's activities over these years is available to replace Meldrum's assertions.

Apart from statics, about which I shall say nothing, there were three chief centres of interest in mechanics in the 1660's:

(1) the motions of pendulums;

(2) the laws of motion;

(3) the free fall of heavy bodies and the motion of projectiles.

In the first the influence of Huygens was dominant; I have placed it so because it was of very lively contemporary concern. The second area of interest descended partly from Galileo and partly from Descartes; the third from Galileo alone. Perhaps one should consider adding a fourth area, the investigation of central forces, but this in fact did not attract much attention as yet.

During his long life Alexander von Humboldt (1769–1859) was mainly connected with three European countries: Germany, France and Russia; nevertheless, he had many scientific and personal relations with England, with British scientists, and with other distinguished citizens of Great Britain. Thus Humboldt's life provides an interesting example of international scientific relations in the nineteenth century. The present paper offers a brief account of this universal and versatile scientist's relations with England in particular.

Before 1600 the most common method of division used in Europe was the galley, batello, or scratch method, and this was still popular up to the end of the eighteenth century. This method is commonly supposed to be of Hindu origin, being based on a method found in India about the fourth century. It will be shown that the Hindu method is identical to the Chinese method of division (ch'u) mentioned in very early Chinese texts such as the Chiu Chang Suan Shu (Nine Chapters on the Mathematical Art, c. first century a.d.). The earliest detailed description of this method is found in the Sun Tzŭ Suan Ching (The Mathematical Manual of Master Sun, third century a.d.).