1110 subject of con1 cleaning is oiic tlint is attracting cvcr-increasing nttcntioii aiiiongst niiiiing cnginccrs in this coiintry, niitl tlic litcriitiirc dcdiiig witli it lins iilrcndy rcnchcd forinidable dinicnsions. ;\lost of its iispccts have IJCCII so tliorouglily iiivcstigntcd and tliscusscd that any iicw work on tlic subject is natiirally cspcctcd to rcncli n 'cry high stnndnrtl. It is to 1)c rcgrcttcd tlint tlie prcsciit work ilccidcdly falls short of aiicli rcnsonnblc cspcetntions in two most iiiiportant respects ; i t s h o w tliroiigliorit cvidcncc of niuch cnrc-Icssncss, and the tlieorcticnl portions arc :is ii riilc iiiore or less iiicorrcct, :ind n t times scrioiisly so. A s n n csninplc (Jf tlic 1:tttcr stntcnicnt it is p-liiips worth irliilc to iinalysc tlic author's trcntniciit of d i n t iiiny bc lookcd upon ris tlic 1J:isnI tlieorcrii of nll gravity scpnrittion, iiiinicly, the derivntion of tlic wcll-know1 mid gcncrnllyiicccptctl Rittinger forllluln. for tlic ultiinntc fiilling velocity of botlics falling freely iii w t c r . Tlicrc is gciicral ngrccnicnt ns to tlic steps by n-liicli this forinuln is rcnchcd, and i t is dillicitlt to iiiitlcrstniid why tlic ilt1t.lior lins iiot a\wilcd himsclf of thc rcpcatcdly publislicd infornintion on thc siibjcct. I-lc coniinciiccs by sc.t,tiiig down n foniiuln for tlic rcsislancc to the niot.ion o f ii body in wiitcr (tic cnlls this tlic '' IZdtly liesistniicc," itltliougli, in fnct, tlic resistance licctl not Iicccssiirily Iiiivc tlic lcnst coiincctioii with tlic formation of cddics), ant1 writes tlic csprcssioii for it iis C d -F W, in ivliicli \V = specific \vciglit of water " iintl " S = density of