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NA TUPE 



SJan. 17, 1878 



a million square miles, that much of it was imper- 

 fectly explored, especially in the north-west. Mr. Riley 

 had to cut short his investigations in British America 

 both for want of time and want of funds. For similar 

 reasons, and on account of Indian troubles, Montana, 

 Wyoming, and Dakota, have been but superficially 

 explored. 



The year 1877 ^^.s an abnormal year, i.e. the insect 

 had, the previous year, overrun a large section of country 

 in which it is not indigenous, hatched, in such country in 

 the spring. This was most fortunate for many reasons, 

 as it enabled the Commission to carefully study the 

 insects in this their unnatural condition, and to carry on 

 experiments with a view of learning how to control them. 

 Much of the work of the Commission was with these 

 young insects. The losses sustained through the devasta- 

 tion of the pest by young and strugglmg frontier popula- 

 tions, ill able to bear them, were immense ; and there was 

 so much discouragement that hundreds and thousands of 

 persons were on the point of abandoning their new homes 

 last spring. At this juncture the Commission went into 

 the field, and by its encouraging predictions (which were 

 all verified) and recommendations, imbued the people with 

 hope and confidence, and drew wes-tward. again the emi- 

 gration that had almost stopped. All ihis work, however, 

 interfered with needed investigations into the proper 

 range, the native home and breedinjj grounds, the source 

 of swarms, and many other important questions which 

 can only be properly studied during a normal year. It is, 

 therefore, very important that the investigations be con- 

 tinued until every question is settled that human investi- 

 gation can settle. 



For the proper settlement of some of the questions the 

 co-operation of the Dominion Government is desirable, 

 and has been promised by the Canadian authorities if the 

 work of the Commission should continue. 



It will be unwise to stop the work of the Commission 

 before completed. The work should be made so thorough 

 as to obviate any necessity in future years of creatmg 

 another commission for the same purpose. After careful 

 estimates it is concluded that the work can be satisfac- 

 torily completed only with two more years' investigation 

 and experiment. The Commission therefore ask for a 

 continuance of the appropriation of 25,000 dols. asked for 

 a year ago. 



There are various other injurious insects of national 

 importance, of which much has yet to be learned, and in 

 addition to completing the locust investigation, the Com- 

 mission contemplate, during the coming two years, 

 studying and reporting on some of these worst enemies 

 to American agriculture. They are especially desirous of 

 reporting on the cotton-worm of the south, which, though 

 often so disastrous to the cotton crop, has never been 

 fully studied^ and in the mere natural history of which 

 there are yet many mysteries and conflicting theories. 



Much has yet to be done in giving practical form to 

 the conclusions arrived at and plans proposed by the 

 Commission to enable the work already done to bear 

 proper fruit. To bring about the needed, co-operation of 

 the two Governments, to cause proper laws to be enacted 

 in all the states interested, and to enforce the truths that 

 alone will make man master of the situation, is largely 

 the work of the future. 



SOUNDING APPARATUS 



''PHAT Sir William Thomson's recent application of 

 -■■ the pianoforte wire to sounding in small depths for 

 the ordinary purposes of navigation is of great value, will 

 be admitted readily by those who are familiar with the 

 present process. But it occurs to me that a formidable 

 objection to its general introduction into naval or mer- 

 cantile vessels is to be found in the necessity of using 

 chemically-prepared tubes for determining the depth of 

 water. Sir William's latest device is (I believe) a straight 





r 



n 



glass tube two feet long, open at one end and inclosed ia 

 a brass tube attached above the sinker, in which air is 

 compressed by the pressure of the water, the amount of 

 compression being determined by the height to which the 

 water rises in the tube. This height is marked by the 

 decolorisation of a coating of chromate of silver on the 

 inside of the tube, effected by the sea- water. A number 

 of such tubes, properly prepared, must 

 therefore be kept at hand, and when 

 once used they must be coated anew, 

 an operation of no little difficulty. 



I have suggested a form of sinker in 

 which these objections are obviated, 

 while the principle is retained. The 

 sinker is of iron three inches in diameter 

 at the bottom, five inches at the top, 

 and 265 inches long. It is cast with a 

 cylindrical cavity, two inches in diame- 

 ter, extending from the top to w^ithin an 

 inch of its base. This cavity contains 

 the glass tube by which the depth is 

 determined. A tube about forty- eight 

 inches long is taken, closed at one end 

 and bent back on itself at its middle 

 point, so as to make two legs each 

 twenty-four inches in length. This is 

 placed inside the sinker (the bend up- 

 ward) and a screw tap, carrying a swivel- 

 link for the sounding line, is screwed 

 over it. Holes in the bottom of the 

 sinker and through the screw tap allow 

 the water access to the tube. As the 

 sinker descends, in sounding, the air 

 within the tube is compressed and the 

 water rises in the open leg. When the 

 column of water reaches the highest 

 point of the bend, the pressure then 

 corresponding to a depth of about five 

 and a half fathoms, any further descent 

 of the sinker will cause the water to 

 pass over into the lower end of the 

 closed leg. The compression of the air 

 will then take place in the upper part 

 of the closed leg, the maximum com- 

 pression being indicated by the length 

 of the column of water remaining in 

 that leg when the sinker is lifted again 

 to the surface. As the sinker is being 

 raised, the air, expanding under the 

 diminished pressure, drives' the water 

 out of the open leg. The inside and outside pressures 

 are therefore equal at any instant. The tube may be 

 graduated in inches and tenths, and a table will give the 

 depth from the reading of the tube. The tuba is then 

 easily emptied and is ready for another cast. The form 

 of the sinker is such that the bend of the tube is kept 

 at a higher level than the open end in case the sinker 

 should fall over when it reaches the bottom — the entrance 

 of surplus water is thus prevented. An ordinary cup 

 attachment for a bottom specimen can be applied to the 

 end of the sinker. 



The tube described will not indicate a depth less than 

 five and a half fathoms. If it is desired to obtain casts 

 in shoaler water a tube with the open leg shorter than the 

 closed leg may be used. One in which the length of the 

 open leg is one-fourth that of the closed leg will indicate 

 depths of two fathoms and upwards. 



I am aware that Sir Wm. Thomson has a tube for 

 bringing up the column of water, but it requires the use 

 of valves, which can never be kept tight under such enor- 

 mous pressures as those to which the sounding-tubes are 

 exposed. 



I inclose a sectional drawing of the above-described 

 tube and sinker. 



Theo. F, Jewell, Lieut.- Com. U.S. Navy 



