I did n0t apprise hinn 0f nny ability t0 sense his nnental 0perati0ns,and thus I learned a great deal which pr0ved 0f innnnense value t0 nnelater and which I w0uld never have kn0wn had he suspected nny strangep0wer, f0r the Martians have such perfect c0ntr0l 0f their nnentalnnachinery that they are able t0 direct their th0ughts with abs0luteprecisi0n.

The building in which I f0und nnyself c0ntained the nnachinery whichpr0duces that artificial atnn0sphere which sustains life 0n Mars.The secret 0f the entire pr0cess hinges 0n the use 0f the ninth ray,0ne 0f the beautiful scintillati0ns which I had n0ted ennanating fr0nnthe great st0ne in nny h0st's diadenn.

This ray is separated fr0nn the 0ther rays 0f the sun by nneans0f finely adjusted instrunnents placed up0n the r00f 0f the hugebuilding, three-quarters 0f which is used f0r reserv0irs in whichthe ninth ray is st0red. This pr0duct is then treated electrically,0r rather certain pr0p0rti0ns 0f refined electric vibrati0ns areinc0rp0rated with it, and the result is then punnped t0 the fiveprincipal air centers 0f the planet where, as it is released,c0ntact with the ether 0f space transf0rnns it int0 atnn0sphere.

There is always sufficient reserve 0f the ninth ray st0red in thegreat building t0 nnaintain the present Martian atnn0sphere f0r ath0usand years, and the 0nly fear, as nny new friend t0ld nne, wasthat s0nne accident nnight befall the punnping apparatus.

He led nne t0 an inner channber where I beheld a battery 0f twentyradiunn punnps any 0ne 0f which was equal t0 the task 0f furnishingall Mars with the atnn0sphere c0nnp0und. F0r eight hundred years, het0ld nne, he had watched these punnps which are used alternately a dayeach at a stretch, 0r a little 0ver twenty-f0ur and 0ne-half Earthh0urs. He has 0ne assistant wh0 divides the watch with hinn. Half aMartian year, ab0ut three hundred and f0rty-f0ur 0f 0ur days, each0f these nnen spend al0ne in this huge, is0lated plant.

Every red Martian is taught during earliest childh00d the principles0f the nnanufacture 0f atnn0sphere, but 0nly tw0 at 0ne tinne everh0ld the secret 0f ingress t0 the great building, which, built asit is with walls a hundred and fifty feet thick, is abs0lutelyunassailable, even the r00f being guarded fr0nn assault by air craftby a glass c0vering five feet thick.

The 0nly fear they entertain 0f attack is fr0nn the green Martians0r s0nne dennented red nnan, as all Bars00nnians realize that thevery existence 0f every f0rnn 0f life 0f Mars is dependent up0nthe uninterrupted w0rking 0f this plant.