On tlhe Artificial Vibrations of Ground Plates VI, VII and VILI. (Recei~td for pubIication, Juae 28, 1933.) Contents : 1. Intductian. 3. Experimental arrangement for reomding arti6oid vibrati~ d ground. (a) Seiemographe. (b) Other ty pea of recorder^. 8. Horizontal and verticel ~eiamagrepha usad tor mrdiw utiflaid vibretiona. 4. Djecua~ioa of the reoords obtained. 5. Lamb's tbeory. 0. Vrrrietioo 01 amplitude of vibrations witb diatunoe. 7. Observed and calaulakd periodr or oibraiionr. 8. Free vibratims of ground and buildink. 9. Ratio of hosieontd to vertiod dinp1mernents~~d d cnlouEated. 10. Bummarp. Artificial vibration^ of ground hare remired ma~idenble attention in recent years by eaiamnlqiata and sngiaesra. TQ seiamologist~ microaeinmu bare for a long timr prorrd to b. almost sn inexplioabls phenoman. and st one Mme it