"Mad Scientists' Club" は次にflying saucerを作る事にしました。
Henry explained that we would have to build it on the principle of a dirigible, with a rigid, but very lightweight frame, covered with an envelope of balloon silk.
"dirigible" は知らない単語で "balloon silk" の意味もピンと来ません。 まず "dirigible" を調べます。
・Macmillan Dictionary: an aircraft like a large balloon (=a bag filled with gas) with an engine
・Wikitionary: A self-propelled airship that can be steered
Etymology: The term arose from attempts in the late 1800s to make a balloon steerable. In French, dirigeable means steerable. Over time the phrase “dirigible balloon” was shortened to just dirigible. In modern parlance, the term has been replaced by airship.
飛行船（airship）の事ですね。飛行船と言うと "blimp" （a small, nonrigid airship or dirigible, esp. one used chiefly for observation）（注： nonrigid: designating a type of airship having a flexible gas container without a supporting structure and held in shape only by the pressure of the gas within.) も頭に浮かびます。
さて、次に "balloon silk" を調べます。しかし、どの辞書にも "balloon silk"の説明は見あたりません。
"balloon" と "silk" を別々に良く調べると "silk" に蚕からで絹以外に次ぎの意味もあることがやっと分かりました。
・American Heritage Dictionary: A silky filamentous material, such as the webbing spun by certain spiders or the styles forming a tuft on an ear of corn.
・Merriam-Webster's Online Dictionary: a filament resembling silk; especially : one produced by a spider
"balloon silk" が蚕の繭を示している訳ではないのが分かってきましたが、"balloon" の意味がまだ分かりません。 しつこく調べるとWikipediaに次ぎの説明がありました。
Ballooning is a term used for the mechanical kiting that many, especially smaller species of spiders, as well as certain mites and some caterpillars use to disperse through the air. Many small spiders use silk to lift themselves off a surface or use the silk as an anchor in mid air. The very fine silk used for ballooning has been called "gossamer" since 1325 and was not originally known to be produced by spiders; by extension, the same word is used metaphorically for any exceedingly fine thread or fabric. Biologists also apply the term "balloon silk" to the threads that mechanically lift and drag systems.（注："gossamer": the very thin light fibers produced by spiders and found hanging on trees and bushes）
なるほど、そこでついでに "baloon silk" と "biology" で google し次ぎの例文を見つけました。
The Journal of Arachnology, 1999にあったRobert B. Suter:氏の論文からの引用です。
A spider attempting to become airborne first climbs to the top of some blade of grass, twig, flower head, or fence post, and then either adopts a ‘‘tiptoe’’stance and emits silk into rising airstreams or drops on a dragline and emits ballooning silk once suspended (Tolbert 1977; Gertsch 1979): either behavior serves to insert both the spider and its silk into moving air.
結論、"Mad Scientists' Club"の作ったflying saucerのenvelope（"the structure within a balloon or non-rigid airship containing the gas" Oxford Dictionary）は蜘蛛（あるいは何かの昆虫）の糸で出来ているようです。
Henry explained that we would have to build it on the principle of a dirigible, with a rigid, but very lightweight frame, covered with an envelope of balloon silk.
"dirigible" は知らない単語で "balloon silk" の意味もピンと来ません。 まず "dirigible" を調べます。
・Macmillan Dictionary: an aircraft like a large balloon (=a bag filled with gas) with an engine
・Wikitionary: A self-propelled airship that can be steered
Etymology: The term arose from attempts in the late 1800s to make a balloon steerable. In French, dirigeable means steerable. Over time the phrase “dirigible balloon” was shortened to just dirigible. In modern parlance, the term has been replaced by airship.
飛行船（airship）の事ですね。飛行船と言うと "blimp" （a small, nonrigid airship or dirigible, esp. one used chiefly for observation）（注： nonrigid: designating a type of airship having a flexible gas container without a supporting structure and held in shape only by the pressure of the gas within.) も頭に浮かびます。
さて、次に "balloon silk" を調べます。しかし、どの辞書にも "balloon silk"の説明は見あたりません。
"balloon" と "silk" を別々に良く調べると "silk" に蚕からで絹以外に次ぎの意味もあることがやっと分かりました。
・American Heritage Dictionary: A silky filamentous material, such as the webbing spun by certain spiders or the styles forming a tuft on an ear of corn.
・Merriam-Webster's Online Dictionary: a filament resembling silk; especially : one produced by a spider
"balloon silk" が蚕の繭を示している訳ではないのが分かってきましたが、"balloon" の意味がまだ分かりません。 しつこく調べるとWikipediaに次ぎの説明がありました。
Ballooning is a term used for the mechanical kiting that many, especially smaller species of spiders, as well as certain mites and some caterpillars use to disperse through the air. Many small spiders use silk to lift themselves off a surface or use the silk as an anchor in mid air. The very fine silk used for ballooning has been called "gossamer" since 1325 and was not originally known to be produced by spiders; by extension, the same word is used metaphorically for any exceedingly fine thread or fabric. Biologists also apply the term "balloon silk" to the threads that mechanically lift and drag systems.（注："gossamer": the very thin light fibers produced by spiders and found hanging on trees and bushes）
なるほど、そこでついでに "baloon silk" と "biology" で google し次ぎの例文を見つけました。
The Journal of Arachnology, 1999にあったRobert B. Suter:氏の論文からの引用です。
A spider attempting to become airborne first climbs to the top of some blade of grass, twig, flower head, or fence post, and then either adopts a ‘‘tiptoe’’stance and emits silk into rising airstreams or drops on a dragline and emits ballooning silk once suspended (Tolbert 1977; Gertsch 1979): either behavior serves to insert both the spider and its silk into moving air.
結論、"Mad Scientists' Club"の作ったflying saucerのenvelope（"the structure within a balloon or non-rigid airship containing the gas" Oxford Dictionary）は蜘蛛（あるいは何かの昆虫）の糸で出来ているようです。
トータル
