明季傳入中國的紅夷大砲，曾在明清鼎革的戰爭中扮演重要角色，此可說是眾所週知之事，然而這些火砲何以能發揮強大威力，先前學界並不甚了然。 筆者在此文中，則嘗試說明當時西方除在鑄砲的設計上較為進步外，更已將操砲所需的數學和物理知識，化約成簡明實用的儀具或計算尺(如矩度、銃規、銃尺、星斗等)，如此即可迅速估算不同仰角下的射程，並判斷如何能用最恰當的火藥，將下同材質的砲彈較準確地擊向目標。這種透過數學以提昇機具操作精密度的方式，可說是西方近代技術革命中一項十分重要的特色，此與中國全憑經驗以發射火砲的傳統方式，形成強烈對比。 筆者希望透過此一研究，能對明末清初西方火砲所以在戰爭中扮演重要角色的原因，有一確切的了解。文中亦將透過火砲測準技術在清代的發展狀況，嘗試理解清廷何以在鴉片戰爭之際無力面對列強堅船利砲的挑戰。

　　　　　It is well-known that European cannons, introduced into China in the seventeenth century, play roles of crucial importance in wars during late Ming and early Qing dynasties, but reasons for their success remain unclear. In this article, the author attempts to explain that the Europeans were not only more advanced than the Chinese in making cannons but also able to transform the necessary mathematical and physical knowledge of ballistics into mechanical calculating devices (such as squadra, sector, sight, etc.) by which gunners could promptly estimate the appropriate amount of gunpowder and angle of elevation to be used in relation to balls made of divergent materials and targets at various ranges. This method of transforming mathematical knowledge into calculating devices features an essential part of the modern technical revolution taking place in the West. It also shows a strong contrast to the method used by the Chinese then, who, while operating cannons, could rely on nothing but experiences. The author hopes that a clearer understanding can be achieved regarding the reason why European cannons could play important roles in wars during late Ming and early Qing dynasties. Besides, at the end, this article will expose to what stage knowledge with respect to the European targeting techniques has developed in the Qing dynasty. It is on the basis of this exposition that the author intends to explain why, after the Opium War, the Chinese failed to resist aggression from the Western countries.