So, we have got this three things that we have discussed now. Now, when you have, we use the reverse of these papers later on. I have to go for the next hour. When you have the engine is connected to the propeller by means of a propeller shaft. So, if I have a diesel engine, how do I know what is the power of the engine? I can measure the indicated pressure inside the cylinder and again calculate the power which is called the indicated horse power or I h p and or I can do a brake test of a engine through a dynamometer and I can get the break horse power or B H P.