我的语法非常差，请问有无人能帮忙剖析一下下面这个句子的语法结构。
Prior to him, all that was known of electricity and magnetism was what the ancients knew, nothing more than that the lodestone possessed magnetic properties and that amber and jet, when rubbed, would attract bits of paper or other substances of small specific gravity.
Prior to him, all that was known of electricity and magnetism was what the ancients knew, nothing more than that the lodestone possessed magnetic properties and that amber and jet, when rubbed, would attract bits of paper or other substances of small specific gravity.
参考译文:在他之前，大家对电磁学的认知还停留在古时候，只了解天然磁铁拥有磁性，与琥珀和黑玉在被摩擦时可以吸附纸片或者其它具备细小重量/比重的物体/物质。
句子语法结构剖析如下:
状语 :Prior to him
主语: all
修饰主语定语从句 ：that was known of electricity and magnetism
系动词:was
表语从句:what the ancients knew
状语：nothing more than that the lodestone possesed magnetic properties and that amber and jet, when rubbed , would attract bits of paper or other substances of small specific gravity
重点单词及短语分析
prior to在…之前;
be known of 对...知道
electricity and magnetism 电磁学
what the ancient knew 古时候人所知道的
nothing more than仅仅，只是
lodestone天然磁铁
magnetic properties磁性
amber and jet琥珀和黑玉/煤玉
when rubbed 当他们相互 摩擦时
rub 摩擦
attract 吸引/吸附
bits of paper 纸片
other substances 其它物质
of small specific gravity 具备小比重的