These winds, now so familiar, extend with a variety of modifications over all the seas of India, from Japan to Madagascar. Their general course is north-east and south-west, with some fluctuations, and they commence blowing from the north-east in October, though it is not till November that they blow steadily from that quarter, and continue to do so for four months. They begin again to fluctuate about the month of March, and do not blow steadily from the south-west till April or May, when they often increase to a strong gale. Previously to the discovery of the monsoons, commercial adventure with the more remote regions of the East had been generally carried on in comparatively small vessels, that crept cautiously along the windings of the coast. As soon however as Hippalus had shown the uniformity of these periodical winds, vessels of a larger and of an improved description were constructed; and so great was the impulse thus given to the trade between Europe and India, that it soon became a subject of apprehension at Rome, lest the empire should be drained of its specie to maintain the commerce with India. According to Pliny,[235] silver, to the value of nearly a million and a half sterling was annually required to pay for the spices, gems, pearls, and silks then imported through Egypt. [Sidenote: Value of the trade with India.] From the earliest historic period, the productions of India have, indeed, been in almost incessant demand by the nations of the West, and from even the mysterious reign of Semiramis, the queen of Assyria, to our own time, the possession of India has been in turn the envy of them all. To Great Britain, India has perhaps been of less special value since the differential duties were abolished and its ports thrown open to the shipping and commerce of the world; but still that empire is a prize she would not readily relinquish. To her merchants it has been a source of immense wealth, and among her people its produce, either as articles of necessity or luxury, is now as eagerly sought after as it was in the palmy days of Tyre, of Rome, or of the Italian republics. Vast quantities of silver are still gathered from all parts of the Western world, for export to the East, in exchange for the products of India; and complaints have been frequently made, even in our own times, of the quantity of the precious metals sent from Europe to pay for these commodities. Yet, so far from this being a just grievance, nothing can be more certain than the prosperity of a people, who have thus at their disposal, from one source or another, vast superabundant stores for exportation and exchange for the raw material or even the luxuries of the East. [Sidenote: The ports through which it was conducted.] [Sidenote: Course of the voyage to India.]