It becomes a giant's task to compute the result when the effect of cross seas, wind at all angles and ever varying force, arched surfaces, head resistance, ratio of weight to area, and the intelligence of the guiding power crop up.

The quote by Lawrence Hargrave describes the complex challenges involved in aerodynamics and the mechanics of flight. Hargrave is emphasizing how various variables, such as cross seas, wind at all angles, and resistance from the air, create an immense task for anyone trying to compute the result of flight. The complexity of managing forces like head resistance, the ratio of weight to area, and the influence of a guiding power all contribute to the difficulty of predicting or controlling flight.

In this context, Hargrave, a pioneer in the field of aviation and flight research, was likely referring to the intricate factors that must be accounted for when designing flying machines, such as airplanes or kites. The interplay of all these factors requires a profound understanding of physics, engineering, and aerodynamics. Hargrave's work was focused on understanding the forces of flight, so this quote points to the immense difficulty involved in designing an object that can overcome such forces and maintain stable flight.

The origin of this quote is tied to Hargrave’s experiments and contributions to aviation technology in the late 19th and early 20th centuries. As an inventor, he experimented with kite designs and was instrumental in the development of early aeroplanes. This quote reflects his understanding of how a multitude of constantly changing factors affect the dynamics of flight.

Ultimately, the quote emphasizes that achieving successful flight requires more than just a simple calculation. It involves the careful consideration of many complex forces, and the intelligence of those guiding the project is crucial in navigating these variables. Hargrave’s words reflect the pioneering spirit of aviation and the scientific approach necessary to solve the problem of flight.