A regular graph has numbers spaced at even intervals, while a log scale graph has numbers spaced at uneven intervals. The reason for this is that while a regular graph uses regular counting numbers like 1,2,3,4, and 5, a logarithmic graph uses powers of 10, such as 10, 100, 1000 and 10,000. To add to the confusion, scientific notation is often used on log scale graphs, so instead of 100 you might see 10^2. Reading a log scale graph is no more challenging than reading a regular X Y axis graph.
Locate the point on the X axis that you want to take a reading for.
Find the corresponding point on the Y axis. Draw an imaginary vertical line with your finger up to the graph and then draw an imaginary line to the left until you cross the vertical axis. This is your Y axis reading.
Convert the number from scientific notation if necessary. For example, if the reading is 10^2, the actual number is 1,000.