February 17, 1888.] 



SCIENCE. 



n 



the premium had been awarded Lewis M. Haupt, professor of civil 

 engineering at the University of Pennsylvania. This discovery of 

 authorship was a surprise to the society, since it was thought that 

 the author of the paper would have proved to be a member of the 

 Coast and Geodetic Survey, of the Hydrographic Office, or of the 

 River and Harbor Improvement Service, a number of the members 

 of which have given much attention to the laws of ocean dynamics 

 in determining the improvements to be made annually by the gov- 

 ernment to our rivers and harbors. The mere announcement, how- 

 ever, of Professor Haupt 's name was confirmatory evidence of the 

 wisdom of the society in awarding the medal. Professor Haupt, 

 although an engineer graduate of West Point, has, during the past 

 twenty years of civil professional life as an engineer, won such suc- 

 cess and distinction in his profession, that the present honor which 

 he has received only re-enforces the views which are gaining such 

 a stronghold, — that the civilian engineer merits a standing in all 

 government engineering work on the same basis as the regularly 

 commissioned officers. 



Tersely, the object of the paper presented to the society was to 

 collate certain observed facts for the purpose of explaining the physi- 

 ■cal phenomena of harbor entrances, and of deducing therefrom 

 conclusions of practical value in the economical solution of the 

 problem of improving the channels and shelterings of harbors. 



What was claimed in the paper as meriting the favorable judg- 

 ment of the society is briefly outlined by the author as follows : — 



" I. The determination of the character, direction, and relative 

 intensities of the forces acting upon any harbor entrance, from a 

 study of the submerged topography and other local physical fea- 

 tures. 



" 2. The discovery of the existence of typical form, in the sandy 

 spits bordering the entrance, which will in general indicate the direc- 

 tion of the resultant movement. 



" 3. The recognition of the fact that the proper place for the ebb 

 discharge, or channel over the bar, is as far removed as may be 

 from the point of direct attack of the flood resultant, when the 

 -direction of the latter is not normal to the coast. 



"4. The definite enunciation of the principle that the trend of the 

 coast with reference to the cotidal line will in general indicate at 

 ■once the proper position for defensive works. 



" 5. The presentation of an original form (in plan) of break- 

 water, whereby the natural agencies are materially aided, without 

 serious interference with either the flood or ebb forces. 



" 6. A method of improvement whereby the internal currents are 

 concentrated and conserved for more efficient .scour after passing 

 the gorge. 



" 7. A plan for utilizing the natural tendencies of the flood to cut 

 a beach channel which shall be available for the lighter-draught 

 vessels. 



" 8. The enunciation of the principle that the cause of the angular 

 movement of the ebb stream after egress is due to the general form 

 of the exterior coast-line, which causes a racing of the tidal crests, 

 from the outer capes towards the bight of the bay, and that the 

 flood components thus generated are the forces which build the 

 bars and shift the inlets. This incessant semi-diurnal action of the 

 flood is the controlling element in the forces affecting the magnitude 

 and position of the bar. Storms and winds may modify and shift 

 the deposits, but eventually the flood re-establishes the original 

 conditions. 



"9. The free circulation and ingress given to the flood by the 

 detached breakwater, so designed as both to oppose the flood and 

 produce interfering waves which deposit sand outside of the chan- 

 nel, whilst it also aids the ebb in its attack on the bar by defending 

 its channel and concentrating its volume. 



" 10. For a given site and stage of water, the flood movement 

 approaches in the same direction, hence the resisting and regulat- 

 ing works should be placed on the near side of the proposed chan- 

 nel. If on the far side, they would be worse than useless, unless 

 for shore protection. 



"II. No artificial re-opening of an outlet which has been closed 

 by this flood component can be maintained without auxiliary works 

 to deflect and modify its action. Dredging is only justified when 

 the interests of navigation are sufficient to maintain a continuance 

 of the expense, and no other reasonable methods are available. 



" 12. The ability resulting from these general principles to con- 

 struct works requiring a lesser linear development which will pro- 

 duce greater navigable depths at less cost. 



" 13. The abolition of the risks and difficulties attending the 

 navigation of narrow jetty entrances in times of danger. 



" 14. It frequently happens that the requirements of navigation 

 and tidal concentration are conflicting : the former demanding 

 wide entrances ; the latter, on account of insufficient tidal volume, 

 narrow ones. This debars the usual jetties, and prevents improve- 

 ment. The plans herein proposed are eminently adapted to meet 

 such contingencies." 



The last-mentioned condition applies in a significant way to the 

 conditions at Absecon and other inlets. 



The phenomena of tidal movements, and their bearing upon the 

 formation and destruction of barriers in harbor basins, are of course 

 influenced not only by the topography of the coast-line, but by that 

 of the bottom of the harbor itself, both of which features are in 

 turn perpetuated or changed in form by the relative resistance of 

 the material forming the bottom of the harbor, and the direction 

 and force of currents due to fresh water and tidal movements, 

 winds, and waves. Yet, at the same time, Uttle has been correctly 

 understood as to the laws governing these movements. The new 

 conditions which Professor Haupt so ably enunciates in his paper 

 throw much light on the study of the history of our offshore water- 

 ways, as shown by an inspection of those extending along the At- 

 lantic coast, as exhibited by the Coast Survey charts. This is 

 particularly realized in an examination of our southern bay, extend- 

 ing from Cape Florida to Cape Hatteras, and of our middle bay, 

 from Cape Hatteras to Nantucket. The application by Professor 

 Haupt, of his principles and discovery to local conditions along this 

 coast-line, is unique and forcible. It is certainly evident to an in- 

 telligent and experienced engineer, as Professor Haupt himself in- 

 dicates, that, if it is proposed to aid nature, the engineer " must so 

 design his external works as to prevent the flood-tide from carrying 

 sand into the channel to obstruct the ebb and require more work 

 of it for its removal." His system is based upon an internal con- 

 centration of the ebb currents in their path to the gorge, and of 

 their external conservation after passing through this section to the 

 ocean. 



A paper narrating a discovery so important in ocean dynamics as 

 this, cannot be fully reviewed or fairly treated in a brief space ; but 

 one of the most convincing arguments in support of the conditions 

 enumerated above is the application of the discovery to the cause 

 and direction of the tidal movements in Barnegat Inlet as bearing 

 upon the location of the light-house which was erected in 1834, but 

 which was subsequently destroyed prior to the erection of the 

 second structure in 1858. This latter structure has been ineffec- 

 tually ' protected ' by a system of jetties, and it is now evident, in 

 the light of the investigation of this particular case, that the struc- 

 ture has been improperly placed on the spit opposed to the flood re- 

 sultant. If the light had been placed on the north spit, the interests 

 of navigation would, no doubt, have been as well protected, and all 

 the defensive works which have been constructed at great cost to 

 the government would have been rendered entirely unnecessary. 



Lentz, in his ' Ebb and Flow of Tides,' says, " The intricate, 

 theoretical, tide-generating conditions are complicated by a number 

 of circumstances, forming a bewildering labyrinth of causes and 

 results, through which the human mind cannot find its way." 

 When one bears in mind such a statement from an authority so 

 high, too much cannot be said in praise of Professor Haupt's dis- 

 covery in its bearing on " useful improvements relating to naviga- 

 tion " as well as " natural philosophy," and of the high honor con- 

 ferred upon him by the American Philosophical Society in award- 

 ing him the Magellanic premium. C. A. A. 



EXPLORATION AND TRAVEL. _ ■ • ,^ 



Notes on the Geography of Labrador. 



The December number of the Bnlleti7t of the American Geo- 

 graphical Society contains a paper by A. S. Packard on the physi- 

 cal geography of Labrador. The paper is accompanied by a 

 map of Labrador, compiled by F. Leuthner, and said to show 

 the present state of our knowledge. It is founded on the British 



