The decreased utility is most clearly seen in the diminished effect which other agents produce when used in connection with the thing. When several are trying to use the same book, and are wasting time trying to get it, we often say their study hours are less fruitful because of the poor library facilities. Again, we speak either of the diminished returns of the field, or of the labor applied to the field. Either the particular thing is said to show diminished returns or the other coöperating agents are said to show them. [Sidenote: Decreasing technical effectiveness of material things] 2. _As the agents used in connection with a fixed amount of any other agent (for mechanical, chemical, physiological, psychological, and other purposes) increase, their objective effectiveness after a given point decreases._ Objective or technical effectiveness means effectiveness independent of the thought or estimate of men. It is not the effectiveness to produce a feeling in men, but to produce results on the material world. In a mechanism, if one part is increased without increasing the other parts, a point is reached where it does not add to the result. If in the building of a bridge the weight of the floor is increased beyond a certain point, the rest of the bridge being left unchanged, the bridge is weakened instead of strengthened. If the weight of the iron in the framework is increased beyond a certain point without strengthening the piers, the structure is weakened. If the pier is greatly enlarged, the bridge may not be weakened, but there is an utter waste of material and effort, and perhaps the main purpose of the bridge is defeated by the damming up of the stream. A bicycle frame, like a chain, is no stronger than its weakest part. If the strength of all parts of the wheel and frame is in equal proportion to the strain they must bear, added weight to any single part weakens the whole machine. The development of the modern type of bicycle, by many experiments, is a good example of the adjustment of materials according to the principle of technical efficiency. A variation of the same principle is seen in chemical combinations. Exact proportions of materials must be used to get a certain result. Increase of one ingredient will not increase the desired product. Either the added part is rejected, does not enter at all into the compound, or it unites to form another and different product. That the same principle holds good of the psychological effects of things, we have already fully recognized in discussing wants and marginal utility. A given amount of a good will affect the senses in a pleasurable way, but an increase in the amount will not cause a proportional addition to pleasure of sight, sound, or smell. On the contrary, such an increase may defeat the object entirely. Here we are at the threshold of the economic problem, for we have touched on "feeling." [Sidenote: Economic diminishing returns relate to value]