30 



^i^7 ^nmfglHoxUl)lu Vis itor. 



well if lliey t'av.e but a i.iicl.lliiiu chance. The 

 lr!;L, or Long Reds, s.e.n lo l,e ul tins drs- 

 ciniion. llouovcr Ml ihi.s n,.iy l.e, it is an mi- 

 ,,o'uu,t iiuinirv uluit soil is l.fst su.led toagivmi 

 Imielv of potMo. We U'..o\v that some a|.|df., 

 astheN.^wloii pippin, must have a deep stion;: 

 soil, and rom.s to iioihinfr « hen p anlfd m a pom 

 soil. And whv should there not he tin- same > . - 

 victv in the hai.its of varieties ot I'O'atnes, as m 

 apples and other i\u\,s?"-MiamrCut^livato,. 



L0Ai)ST^7r^7T^^^rT7i^St.PEa.0R.-We 



find the tollowinir interesiin« Icuer in " I" « " 



berofthe I><-iroii Daily A.lveruse.-. •'■ 1'" -r"- 

 ton, jr., isa hrother of the Uue eminent geolojjist. 



Dr. Douglass Houghton, of ft!"-l"f;'"= g,. 

 Dktuoit, Dec. 1», J04O. 



Mr. Editob: Amons H"^ '"<'">■ <lis'--"vcrips 

 which have heen ma.le in the miiuTal re.ioi o 

 Lake Superior dnrin;.' the past season, H'-^"^ '"^^ 

 Len one which thouf-h of less importance than 

 many othn-s, is of ^reat interest to the man ol 

 science I refer to the discovery ol name load- 

 stone, a varVty of the H';i''"V-,"';>f^'";V''n" u'lTo 

 It was discovered hy Hela Huhhaid, bsq., who 

 was carryins on a f:eolo.u'ical, in connexion vMth 

 a Ui.ited'Slat.s linear survey, and who has col- 

 lected the only specimens ever ohlained in that 

 re'.ion He was led to the discovery by noticing 

 the jrreat nnctuaiions in li.e hearing of the mag- 

 netic needle, lis locality is Middle sland, which 

 is two miles northwesterly from Presqne Isle 

 The island is trranile, traversed by dvUcs ot 

 greenstone trap, in two of « hich (havmira conrse 

 iiearly north and south,) ihe loadstone was ionml 

 It is 'of a cr^sialine or arannhir structure, and 

 li.i.dit, by sliuht examination, he mistaken lor a 

 vaHety of jxranile. It exhibits polarity, the op- 

 posite sides of the .same sp.-cimen, attractin-and 

 repellins the north end of the needle. It .also at- 

 tracts iron tilinfis. The loadstone of .lifieren 

 portions of these dykes wns observed to exliilnt 

 different powers of naiL'iielisni. 



Ahhon-hthis portion of the mineral region 

 had heen thoroushlv examined by competent ^rc- 

 olo"ists duriiif; a perioil of several years,/yct tlie 

 existence of native loadstcme remained imknnwn; 

 and this circumstance isa f.irther proof of the 

 imnerfect knovvled-e we have of the vaiions mm- 

 era'ls of that intereslinj,' country, and that the 

 richest di.-icoveries and develn|mients may jet 

 remain to be made. 



Yours respectfully, 



J. HOUGHTON, Jr. 



Thames Tuunel. 



The city of London is built on both sides of 

 tlie river Thames, and extendiii}' along its banks 

 for a considerable distan.'C. The two parts ol 

 the city that are thus separated by the river, are 

 connected at its upper part hy the means ot sev- 

 eral -uific.^nt hridn-s. FUit the city rxlen.ls 



down the river so far, that ihe lower parts can 

 „),t be connerted by a bridKO in this way, lie- 

 raiise a bridge uould be such an obstruction to 

 the multitude of ships that are constantly arm- 

 in.' and dop;n-rmg.- Yet these (larls of the city 

 are very bu.slling and busy parts, ami it was (omid 

 to be almost necessary to have some way of 

 communication between them, liir all the carts 

 and carriages ihat p.assed from one side to the 

 other, thon..:li the distance across the river in a 

 Blrai'dit line was only about twelve hundred feet, 

 liad "to go lour miles round to ci-oss LomUm 

 Bridge. " 'J'his will give an idea of the immense 

 gi/.e of the citv. 



This w;is so inconvenient, that peojile begun 

 to think aboHt conBlriiclliig a tunnel under the 

 bed of the river. SevKial attempts were ma<le, 

 bill thcv vVere nusuccessfnl. At length a celebra- 

 ted I iigineer, named Brunei, proposi'd an elilire- 

 Jy new plan, wbicdi succeeded. He got it Irom 

 walching the proieediiigsof a little insect which 

 bores its way into wood, and especially into the 

 Jioiloins of ships. This insert, called the teredo, 

 Ims a hard round :hell, and it was this shell, and 

 (lie manlier in which the insect worked under n, 

 tlial gave the cngiiiueer the idea of the ingeni- 

 <,us machine, by means of which the tunnel was 

 du". The (ili.'ineer began the iww attempt in a 

 siie^nhir way — with buihlmg a circular brick wall 

 .npon the to'p of the ground to ke.'P out ihe wa- 

 ter. When it was built Miliicienily high, rtlr. 

 ISrmiel r.<;t hi^ workmen to digliiug away 1 he 

 earth vvilliin and imderiiealh it. Of course us the 



earth was taken away, it settled down of itself,! 

 and when its top got below the snrlace of the 

 -round, the masons went on building it up, so 

 That its top might always be level with the earth. 

 Thus hy this ingenious coiitrivauce the sides ol 

 his shaft were always securely lined with brick, 

 .•xeeiit the little space at the bottom where the 

 n'leii were at work, and thus the water was kei-t 

 lioni Hilling in, and the earth from caving in.-- 

 The earth was raised, and the water which did 

 run in at the bottom pumped out by a sleam-en- 



^"wheii he had dug his shaft deep enough, Mr. 

 Brunei built his great machine, whtcl, was to 

 nierce a broad road right under the bed of the 

 I.reat river. This consisted of a huge Irame the 

 size of Ihe archway that was to be dug, built as 

 <.|.-oip' as limber and iron could make it, and di-, 

 vii'.e.liiito twelve separate compartments, each 

 eontainini:- three cells, one above another, just 

 lai-oe enoVmh tor a laborer to %yorU in ; the rest 

 was strong timber. Thuslfiere were in reality 

 tv.elve machines along side of each other, and 

 precisely similar. The whole together was call- 

 ed the s'liidd. The front of Ihe shield was cover- 

 ed with small moveable boards. This was the 

 great teredo which was to pierce Ihe bottom ot a 

 "■real river. , . _ , , 



The mode of working it was this. Each work- 

 man standing in his cell look down one ol the 

 moveable boar.ls, dug about six inches into tlie 

 earth and firmly liisiened back the hoard, took 

 down anoiher and did the same. Thus, piece- 

 meal, six inches of space was cleared <'0"i ''f 

 line Ihe whole machine. The object of the little 

 boards wa?, by leaving only a small surface ex- 

 posed, to pri'vent the earth caving in and hury- 

 incr the v%orkmen. This was absolutely necessa- 

 rvf for sometimes the earth they [lassed through 

 was so soft and wet as to be little better than 



'"when iho wliolc sjiace had been cleared from 

 belbre lh«-' machine, then by means of screws 

 res;iu"-a.'aiiist the part of the wall that was al- 

 i-eady^baili, each of the divisions of the mstru- 

 meu'l VNas moved forward, and tlie workmen be- 

 ..au a.'idn. This left six inches of the passage 

 behind the machine, without any brickwork to 

 support it ; hut this narrow space was snpporied 

 by the projeciing shield until the masons built up 

 their strong brick arch to support it. 1 bus the 

 i-ieatworm en pt along, slowly catmg its way, 

 down under the water, while ships were sailing 

 over its head. For the first nine feet it passed 

 lln-ouiih the solid clay, and all went well but 

 then they came to loose, watery sand, and lor 

 Ihiriv-iwo anxious days were in great tear that 

 ,he I'lver would break through. On the 14th of 

 Mtuch, ISati, it was discovered that there was a 

 'neat caviiy in the river's bed. At high tide the 

 miners heard the uproar of the fallmg ^'"1 "I'f" 

 the beail of their good shiehl, and saw bursts ot 

 water fidlow ; but tliey had taken precaution, so 

 ,hat no injury ensued; and the river itself soon 

 liiied up the hole with mud. 1 he same thing 

 happened afterwards, so that they at last luul o 

 examine the hod of the river with a divmg-hc , 

 and where there were boles, fill them up with 



'■'h was not till May, TS'27, that any serious acci- 

 dent occurred. Then some vessels coming m 

 when the ti :e was low, moored just over the spot 

 where iho shield was at vvork, and the obstrnc- 

 ,i„n llK-y presented to the water caused a great 

 bole to be washed away. Through lliis bole the 

 water rushed with such violence as to force the 

 workmen out of their cells, ami comijel them to 

 hasten out of the tunnel to save their lives. 1 he 

 bole was examini'd from above with a diving-bel , 

 a,„| three thousand hags .if clay were used 10 f^l 

 it In Ihe course of a month, the great sleaui 

 ei",iine liad'pum|.e<l the tunnel tiee of waler,imd 

 the workmen began to clear a\vay the miid. 1 he 

 brick was lijimd lobe perfectly sound, ihmigh 

 Iheforce of the water had been such that the 

 .rreat chains which iini!ed the divi-ions <d 111 

 shield were snapped asunder, and the hrick-work 

 next the shield was worn to half its ihickncss.- 

 in.Iamiarv, IS'iS, the middle ol the river was 

 riNiched, tiiough not williont great danger. . ome 

 thing or olher was constantly occniing to eNcile 



"'1'5'u't' in August of this year an irrniMion look 



place, so serious lliat it had nearly preyented the 



i eoiiipletion of the tunnel altogether. 1 ho water 



and mud completely filled it, and six or seven 

 men were overtaken and iierished. The engi- 

 neer's son was only saved by being near the en- 

 trance, and being carried hy the water up the 

 shaft. Four thousand tons of clay in bags were 

 put into the hole belore it was closed. When 

 the tunnel was pumped out, the work was found 

 uninjured ; but the comiiany had spent all their 

 money, anil were discouraged by repi-ated acci- 

 dents; iiiid by the great difficulty of carrying the 

 work any liirtlier. For seven years it was shut 

 np, and nothing was done. At length the gov- 

 ernment of Great Britain agreed to furnish some 

 money, and to the great joy of Mr. Brmiel, the 

 work 'was begun again in January, 16:3o. ror 

 fifty weeks they proceeded only about two feet 111 

 a week, and then for twelve weeks they only dug 

 twelve feet in Ihe whole. The ground was so 

 soft that they actually bad to mahc a bed belore 

 hand by lettnig down clay to the bottom ol the 

 river, and then to dig through it. Yet under -al 

 these difficnhies, Mr. Brunei actually removed 

 the old shield, which had become worn and in- 

 jured, and replaced by a new one. 



Two or three more irruptions took place, but 

 no more lives were lost, and at lerngth Mr. lirniiel 

 had the pleasure of passin- down a shaft on the 

 other side of the river, and through a narrow 

 iiassaw into ihe tunnel. How happy must he 

 have "felt when he saw the work of so many 

 years of toil and anxiety now almost completed, 

 ■perhaiis there was not another man 111 the conn- 

 ,rv wh.o would b:.ve finished such a work in the 

 face of such difficnItiHS and discouragements. 



The tunnel is now finished and in constant use. 

 It consists of two arches one thousand two hun- 

 dred feet lorn.', each wide enough fi.r a carnage 

 way and foot-i.ath, and lighted by gas: and in 

 the great shaft at each end are spiral roads lor 

 earts, and stair-cases for passengers. The whole 

 work cost three million and seventy thousand 

 dollars.— T/(ci^;»cnrf. 



Breadstuffs in Great Britain. 



The nnanlitv of wheat under lock in the Uni- 

 ted Kiugdon,,"ou the 5ili of November, accord- 

 in.' to the Mark Lane Express, was but MO.COO 

 hu-hels, ai!ainst.5,0-!4,0C0 bushels for the corres- 

 ponding period last .year. The fiuantiiv "' '"'"'r 

 under lock at the same lime, was only 12&,tUU 

 barrels, aiiaiisl 130,000 barrels at the corr.'spoud- 

 in.' perioil in 1845. Of Ihe slock of free floor of 

 bonie or foreign growth, no statement is lurnisli- 



i'he same excelbMit authority, nowever, informs 

 us that the imports of wheat and wheaten flour 

 into Ihe United Kingdom, to the same date, were 

 tonal 10 about siXTV-rouu millions ot wheal, 

 showing that the enormous .piantity of sixty- 

 two MILLIOXS FOUR HU.NBKED AND THIRTY Tlloi;- 



SiM> bu.-hels had heen entered for consumplion, 

 or disposeil of in fome olhcr way in the space ot 



ten months. , ,- 1 i-- 



But this cxttaordinary demand of the Ivmg- 

 .loiii diirinir the present year upon the resources 

 of olhcr countries, apprars in -slronger light when 



compared with the imports of that countiy in 

 prewious years. ^ , ■ 



The returns made to Parliament of the imiioi- 

 tatians of wheal and wheaten Hour, Fm-cign as 

 well as Colonial, inU) the United IV,",-' ".",'"' \','" 

 years ending the .'.th of Ja'.uary, 1^4',', 1t4._5, 1^44 

 and 1845, yive the following figures. 1 he return 

 is made in'Unarlersof Wheat— we put it 111 In.sll- 

 els .and in round numbers. 



1841, 



184-3, 



1843, 



1844, 



22,200,000 bush. 



24,:«I0,(H)0 " 



8,,'St!0,(i('0 " 



11,000,000 " 



Total, (;g.ooo,oio " 



In ten months of the present year, the imports- 

 have been sixtv-koi'R mili.io.x ei-shf.ls, ,uid at 

 the same rale for the remaining iwo mouths ot 

 ll,e y. ar, the enormous .pianlily of si-venty-six 

 Mll.IION F.lGllT nuNnRF.nTiiousAxn«Ls.i-:i.s will 

 Irive leeii iinporle.l, greater by more than 10,- 

 000,000 than the imports of four previous conscc- 



""of'lli'e mianliiv furnished by this country In- 

 wards so large an import as that ot the present 

 year, we have no data by which 10 furnish any 

 ■reliable eslimate. But, if ^^c may judge ol the 

 prc-sent by the past, the qnaiiliiy tent lorward l>y 

 is has beiii inconsiderable in sy largo an iinpoi- 



