44^ PRIZE QUESTIOXS OF SCIENTIFIC SOCIETIES. 



4. Question 112. A difference of opinion still existing as to what 

 machine now in use is the best adapted for raising water, we in- 

 quire — 



a. Is any one of those machines to be preferred under all cir- 

 cumstances and without reference to the description of the motive 

 power ? 



h. In the negative case, what are the conditions which should 

 entitle any one of those machines to the preference? 



c. What, in order to obtain the best results, should be the dimen- 

 sions of the hydraulic machines adapted to use in our ordinary large 

 •draining works? 



The reply should be based upon exact observations and experi- 

 ments, and must in every case be corroborated in the most con- 

 vincing manner. 



5. Question 114. During many years the learned and scientific have 

 discussed the question of the possibility of building enclosed seaports, 

 similar to those of northern and southern Holland, and intended 

 for the safe sheltering of vessels of considerable draught of water. 

 Some of those who have discussed the question maintain that in the 

 present state of practical science there is no difficulty in the formation 

 of such harbors. We therefore ask for a complete plan of a coast 

 harbor, similar, for instance, to that of Scheveningue, which at Ioav 

 water shall admit vessels drawing twenty-one feet, and with an en- 

 trance of sufficient breadth to allow such vessels an easy entrance 

 with wind blowing hard from the northwest. To such plan there 

 should be added an estimate of the cost of the construction as well 

 as of the annual repairs. 



6. Question 116. Therheumameters of Brunings, Woltman, Pitot, and 

 others, have this disadvantage: that while they indicate the relative 

 value of velocities they do not indicate their absolute value; and the 

 rheumameter of Kraijenhoff is adapted to the examination of only 

 some portions of rivers. We therefore require an instrument calcu- 

 lated for ascertaining the mean velocity in any part of a river, and 

 free from all the known defects of existing inventions, or having 

 such defects remedied as far as possible. 



7. Question 1 17. The history of the changes which have taken 

 place in the course of rivers and in their mouths, as well as of the 

 events which have been the causes or the results of these changes, is 

 of the utmost consequence to obtaining a knowledge of the exist- 

 ing state of our rivers. Many things worthy to be known on this 

 subject are scattered through individual dissertations, and in the 

 debates, reports, resolutions, and memoirs of various learned and scien- 

 tific societies. It would be useful to collect these things and make 

 them known to the persons iliterested. Therefore, we suggest: "A 

 judicious historical memoir on the rivers of Holland from the inunda- 

 tion of the Zindhollandsche Waard to the present time." 



8. Question 118. Other countries already possess locks of extraor- 

 dinary dimensions, and the necessity may arise for building similar locks 

 in this country. We therefore solicit : "A critical description of the 



