76 EKMAN. ON DEAD-WATER. [norw. pol. EXP. 



Fifth column, The additional "starting force" by which the constant 

 towing-force was augmented at the beginning of some experiments, in order 

 to give the vessel its constant velocity more quickly: it is half of the addi- 

 tional "starting weight" suspended. 



Sixth column, The distance traversed by the boat-model before the addi- 

 tional starting-force was removed; it is twice the distance during which the 

 starting-weight was allowed to act. 



Seventh column, The constant towing-force on the vessel in grammes. 



Eighth column, The force which is necessary to give to the vessel its 

 actual acceleration at a given, definite instant. (For the calculation of this 

 force, see the next section of this chapter). In this column, a value is given 

 only in those cases in which the velocity gradually increases or decreases 

 towards its final value. When there were oscillations in the velocity, the 

 eighth column is blank. 



Ninth and tenth columns, Corresponding values of resistance and velocity 

 under uniform motion. Ninth column gives the towing force diminished by 

 the quantity in the eighth column, i. e. the force necessary to draw the vessel 

 uniformly with its actual velocity; this latter is given in cm. per second, in 

 the tenth column. Both quantities then refer to a definite instant during the 

 experiment. "Maximum resistance" written in the eleventh column, denotes 

 that resistance and velocity are given for that moment, during the whole ex- 

 periment, at which the acceleration of the boat-model was smallest. In several 

 cases (when there were velocity-oscillations) the tenth column gives the mean 

 value, about which the velocity seems to have oscillated ; and the accelerations 

 are disregarded. In these cases, the eighth column is blank, and the ninth 

 column gives the same value as the seventh column. When the estimation of 

 the mean velocity in the tenth column is uncertain, the value is enclosed in 

 brackets. From some experiments it was quite impossible to determine a value 

 of velocity and corresponding resistance. Experiment No. 55 is such a case, 

 and here will be found in the tenth column. < 8'1 ; this indicates that the velo- 

 city increased up to 8*1 cm. per second and then slackened again. 



In some cases, the diagrams representing the velocity of the boat-model 

 during the whole experiment, are inserted (in PI. VII— VIII). These experi- 

 ments are denoted in the tables, by an asterisk with the number in the second 



