Figure 1. Influence of temperature on the solubility of potassium nitrate in water.

Figure 2. Variation of ionization current with increasing magnetic field.

Figure 3. Illustration of how the reader becomes confused as to where he is in your outline if he fails to distinguish between your types of headings.

Figure 5. The general problem is made up of a number of broad problems, these broad problems are made up of a number of specific problems, and the specific problems, in turn, usually are made up of a number of closely related subproblems. The solution of a problem at one level contributes to the solution of the problem at the next higher level. The general problem, the broad problem, and the specific problem seldom are completely solved; that is, there usually is room for more research in every field. Ordinarily, many different groups of authors contribute to the solution of the broad and general problems; whereas prior to the publication of your paper, your group will be the only one working on your specific problem, unless some group elsewhere independently has got the same idea.